pythonRelaxDepsHook: make distribution name matching case insensitive

Is it PyOpenSSL or pyOpenSSL or pyopenssl? With this change you don't
have to care. Write it as pYoPeNSsL for all I care¹.

Can we do it like that? Yes, we can. Distribution names should be matched
with `re.IGNORECASE` according to the wheel specification².

[1] https://packaging.python.org/en/latest/specifications/core-metadata/#name
[2] Just kidding, please make it look sane.

pkgs/development/interpreters/python/hooks/python-relax-deps-hook.sh

@@ -52,7 +52,7 @@ _pythonRelaxDeps() {
     else
         for dep in $pythonRelaxDeps; do
             sed -i "$metadata_file" -r \
-                -e "s/(Requires-Dist: $dep\s*(\[[^]]+\])?)[^;]*(;.*)?/\1\3/"
+                -e "s/(Requires-Dist: $dep\s*(\[[^]]+\])?)[^;]*(;.*)?/\1\3/i"
         done
     fi
 }