copyright: make repository REUSE compliant

Add licensing and copyright information for all files in this repository. This
either happens in the file itself as a comment header or in the file
`.reuse/dep5`.

This commit also adds a Github workflow to check pull requests and adapts
copyright.pl to the changes.

Closes #8869

1 files changed, 2 insertions, 0 deletions

diff --git a/maketgz b/maketgz
index 9869aa105..92ea871af 100755
--- a/maketgz
+++ b/maketgz
@@ -22,6 +22,8 @@
 # This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
 # KIND, either express or implied.
 #
+# SPDX-License-Identifier: curl
+#
 ###########################################################################
 
 version=$1