CI: enable monthly Fedora Rawhide clang builds

that was temporarily disabled due to
https://github.com/haproxy/haproxy/issues/1868

we are unblocked, let us enable clang in matrix
diff --git a/.github/workflows/fedora-rawhide.yml b/.github/workflows/fedora-rawhide.yml
index 36ab7c1..7e735a3 100644
--- a/.github/workflows/fedora-rawhide.yml
+++ b/.github/workflows/fedora-rawhide.yml
@@ -11,9 +11,7 @@
   build_and_test:
     strategy:
       matrix:
-        cc: [ gcc
-#             ,clang  # commented due to https://github.com/haproxy/haproxy/issues/1868
-            ]
+        cc: [ gcc, clang ]
     name: ${{ matrix.cc }}
     runs-on: ubuntu-latest
     container: