Fixes: #7258
Change-Id: I3577f665eca04f2632b69bcb090f0a4ec9271db9

The :meth:`_engine.Inspector.reflect_table` method now supports reflecting
tables that do not have user defined columns. This allows
:meth:`_schema.MetaData.reflect` to properly complete reflection on
databases that contain such tables.   Currently, only PostgreSQL is known
to support such a construct among the common database backends.

Fixes: #3247
Closes: #7118
Pull-request: https://github.com/sqlalchemy/sqlalchemy/pull/7118
Pull-request-sha: cb8ce01957e9a1453290a7c2728af8c60ef55fa1

Change-Id: I906cebe17d13554d79086b92f3e1e51ffba3e818

Fixes: #6999
Change-Id: I29cf3908a6c872611409a3e7256296314c81dea1

<!-- Provide a general summary of your proposed changes in the Title field above -->

### Description
`__class_getitem__` to support generics was introduced in Python 3.7.
In 3.9 some built-ins were made generic but the functionality
for user-defined classes has been there since 3.7.

### Checklist
<!-- go over following points. check them with an `x` if they do apply, (they turn into clickable checkboxes once the PR is submitted, so no need to do everything at once)

-->

This pull request is:

- [ ] A documentation / typographical error fix
	- Good to go, no issue or tests are needed
- [x] A short code fix
	- please include the issue number, and create an issue if none exists, which
	  must include a complete example of the issue.  one line code fixes without an
	  issue and demonstration will not be accepted.
	- Please include: `Fixes: #<issue number>` in the commit message
	- please include tests.   one line code fixes without tests will not be accepted.
- [ ] A new feature implementation
	- please include the issue number, and create an issue if none exists, which must
	  include a complete example of how the feature would look.
	- Please include: `Fixes: #<issue number>` in the commit message
	- please include tests.

**Have a nice day!**

Closes: #7049
Pull-request: https://github.com/sqlalchemy/sqlalchemy/pull/7049
Pull-request-sha: 7bd16d416db010e7140313fe326861cc263b8864

Change-Id: I4f45b9585d263636e613cc5c86e710fa31c7d283

* fix: lib/sqlalchemy/sql/lambdas.py

* fix: lib/sqlalchemy/sql/compiler.py

* fix: lib/sqlalchemy/sql/selectable.py

* fix: lib/sqlalchemy/orm/relationships.py

* fix: lib/sqlalchemy/dialects/mssql/base.py

* fix: lib/sql/test_compiler.py

* fix: lib/sqlalchemy/testing/requirements.py

* fix: lib/sqlalchemy/orm/path_registry.py

* fix: lib/sqlalchemy/dialects/postgresql/psycopg2.py

* fix: lib/sqlalchemy/cextension/immutabledict.c

* fix: lib/sqlalchemy/cextension/resultproxy.c

* fix: ./lib/sqlalchemy/dialects/oracle/cx_oracle.py

* fix: examples/versioned_rows/versioned_rows_w_versionid.py

* fix: examples/elementtree/optimized_al.py

* fix: test/orm/test_attribute.py

* fix: test/sql/test_compare.py

* fix: test/sql/test_type_expression.py

* fix: capitalization in test/dialect/mysql/test_compiler.py

* fix: typos in test/dialect/postgresql/test_reflection.py

* fix: typo in tox.ini comment

* fix: typo in /lib/sqlalchemy/orm/decl_api.py

* fix: typo in test/orm/test_update_delete.py

* fix: self-induced typo

* fix: typo in test/orm/test_query.py

* fix: typos in test/dialect/mssql/test_types.py

* fix: typo in test/sql/test_types.py

Fixed bug where the error message for SQLite invalid isolation level on the
pysqlite driver would fail to indicate that "AUTOCOMMIT" is one of the
valid isolation levels.

Change-Id: Icbceab9a28af6a560859761fa92320b5473269a9
References: #6959

The setup requirements have been modified such ``greenlet`` is a default
requirement only for those platforms that are well known for ``greenlet``
to be installable and for which there is already a pre-built binary on
pypi; the current list is ``x86_64 aarch64 ppc64le amd64 win32``. For other
platforms, greenlet will not install by default, which should enable
installation and test suite running of SQLAlchemy 1.4 on platforms that
don't support ``greenlet``, excluding any asyncio features. In order to
install with the ``greenlet`` dependency included on a machine architecture
outside of the above list, the ``[asyncio]`` extra may be included by
running ``pip install sqlalchemy[asyncio]`` which will then attempt to
install ``greenlet``.

Additionally, the test suite has been repaired so that tests can complete
fully when greenlet is not installed, with appropriate skips for
asyncio-related tests.

Fixes: #6136
Change-Id: I8f3a1c00a4a8b6a273484af1da1f7aaadf588ae7

… so third-party dialect testing won't fail with:

"AttributeError: 'Requirements' object has no
attribute 'implicitly_named_constraints'"

Change-Id: Iafa3e36f3dd169c338dd6eaee21c73aa35e854cc