.github: install meson for CodeQL.

.github/workflows/codeql.yml

@@ -60,6 +60,10 @@ jobs:
         # For more details on CodeQL's query packs, refer to: https://docs.github.com/en/code-security/code-scanning/automatically-scanning-your-code-for-vulnerabilities-and-errors/configuring-code-scanning#using-queries-in-ql-packs
         # queries: security-extended,security-and-quality
 
+    - name: Prepare Build Environment
+      run: |
+        apt update
+        apt install --yes meson
 
     # Autobuild attempts to build any compiled languages (C/C++, C#, Go, Java, or Swift).
     # If this step fails, then you should remove it and run the build manually (see below)