feat(ci): Add support for .codeqlversion

Author: GeekMasher

.codeqlversion

@@ -0,0 +1 @@
+2.20.1

.github/actions/install-codeql/action.yml

@@ -26,6 +26,12 @@ runs:
         CODEQL_HOME: ${{ github.workspace }}/codeql_home
         CODEQL_CLI_VERSION: ${{ inputs.codeql-cli-version }}
       run: |
+        if [ -z "$CODEQL_CLI_VERSION" ]; then
+          echo "No CodeQL CLI version specified. Reading from .codeqlversion file."
+          CODEQL_CLI_VERSION=$(cat ./.codeqlversion)
+        fi
+        echo "Installing CodeQL CLI v${CODEQL_CLI_VERSION}."
+
         mkdir -p $CODEQL_HOME
         echo "Change directory to $CODEQL_HOME"
         pushd $CODEQL_HOME