ci: Update to codeql-action v3

Silences a harmless deprecation warning.

.github/workflows/check.yml

@@ -178,7 +178,7 @@ jobs:
     steps:
     # Initializes the CodeQL tools for scanning.
     - name: Initialize CodeQL
-      uses: github/codeql-action/init@v2
+      uses: github/codeql-action/init@v3
       with:
         languages: ${{ matrix.language }}
         # If you wish to specify custom queries, you can do so here or in a config file.
@@ -211,7 +211,7 @@ jobs:
       # Can't use `meson compile` here because Ubuntu 20.04 is too old
       run: ninja -C _build
     - name: Perform CodeQL Analysis
-      uses: github/codeql-action/analyze@v2
+      uses: github/codeql-action/analyze@v3
 
   valgrind:
     name: Run tests in valgrind