ModuleNotFoundError was introduced in Python 3. It is raised when the
module does not exist. On the other hand, ImportError is raised during
any import failure. For example, a syntax error or other runtime error.

Using ModuleNotFoundError means that errors unrelated to a missing
package will be propagated to the user. PyJWT doesn't know how to handle
these.

This also allows more functions to always be available for import

Now that Python 2 is not supported, can move away from type comments to
type annotation 🎉.

The typing module is always available, so remove the guards.

Specify the supported Python in the mypy configuration.

Move other mypy configurations to one place. This way, whether tox is
used or not, the same mypy errors appear.

Distribute and install PEP-561 compliant py.typed file. When PyJWT is a
imported as a library, this tells mypy to use the provided type
annotations rather than going through typeshed. This way, the types are
always up to date when running mypy.

Remove outdated ignores since dropping Python 2.

* Drop support for legacy contrib algorithms

* Update cryptography dep

pyupgrade is a tool to automatically upgrade Python syntax for newer
versions of the language. Running pyupgrade removes several
Python-2-isms that are no longer necessary now that the project is
Python 3 only.

https://github.com/asottile/pyupgrade

* Setup pre-commit hooks

* Run initial `tox -e lint`

* Fix package name

* Fix .travis.yml