Revert "setup: require jinja<3.1 to prevent breakage"

This reverts commit d120a385.

The change introduced unwanted side-effects which would only get worse
with time.

distro/pkg/nix/default.nix

@@ -14,11 +14,6 @@ python3Packages.buildPythonApplication rec {
     sha256 = "FIXME"; # would be {{ src_hash }} if tarball was used
   };
 
-  # Old jinja2 isn't in nixpkgs anymore.
-  postPatch = ''
-    substituteInPlace setup.cfg --replace 'jinja2<3.1' 'jinja2'
-  '';
-
   propagatedBuildInputs = with python3Packages; [
     # copy&pasted requirements.txt (almost exactly)
     beautifulsoup4   # upstream version detection

requirements.txt

@@ -4,7 +4,7 @@ build            # apkg distribution
 cached_property  # @cached_property for python <= 3.7
 click            # nice CLI framework
 distro           # current distro detection
-jinja2<3.1       # templating (COMPAT: <3.1 in order not to break systems, apkg works fine)
+jinja2           # templating
 packaging        # version parsing
 requests         # HTTP for humans™
 toml             # config files

setup.cfg

@@ -27,7 +27,7 @@ install_requires =
     cached_property
     click
     distro
-    jinja2<3.1  # COMPAT: <3.1 in order not to break systems, apkg works fine
+    jinja2
     packaging
     requests
     toml