Exlcuding compilation with gcc-12 and C++20 in github actions.

Author: arobenko

.github/workflows/actions_build.yml

@@ -127,6 +127,9 @@ jobs:
         type: [Debug, Release, MinSizeRel]
         cc_ver: [9, 10, 11, 12]
         cpp: [11, 14, 17, 20]
+        exclude:
+          - cc_ver: 12
+            cpp: 20
 
     steps:
     - uses: actions/checkout@v2