[CI] Remove GCC 15 as it is not yet available.

Author: vyazelenko

.github/workflows/ci.yml

@@ -131,7 +131,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        version: [ '11', '12', '13', '14', '15' ]
+        version: [ '11', '12', '13', '14' ]
     env:
       CC: gcc-${{ matrix.version }}
       CXX: g++-${{ matrix.version }}

.github/workflows/codeql.yml

@@ -146,7 +146,7 @@ jobs:
       fail-fast: false
       matrix:
         language: ['cpp']
-        version: [ '15' ]
+        version: [ '14' ]
     env:
       CC: gcc-${{ matrix.version }}
       CXX: g++-${{ matrix.version }}