chore: update libver and add release test

.github/workflows/tests.yml

@@ -65,4 +65,22 @@ jobs:
                 composer install
                 composer global require phpstan/phpstan
                 ~/.composer/vendor/bin/phpstan analyse
+    libver-check:
+        runs-on: ubuntu-latest
+        name: Verify Google\Client::LIBVER
+        steps:
+
+            - uses: actions/checkout@v2
+            - name: Setup PHP
+              uses: shivammathur/setup-php@v2
+              with:
+                php-version: '8.1'
+            - name: Verify libver
+              run: |
+                  LIBVER=$(php -r 'require "src/Client.php"; echo Google\Client::LIBVER;')
+                  RELEASEVER=$(php -r 'preg_match("/## \[(\d.\d+.\d+)\]\(/", file_get_contents("CHANGELOG.md"), $matches);echo $matches[1];')
+                  if [ "$LIBVER" != "$RELEASEVER" ]; then
+                      echo "Google\Client::LIBVER ($LIBVER) does not equal the current release ($RELEASEVER)."
+                      exit 1
+                  fi
 

src/Client.php

@@ -52,7 +52,11 @@
  */
 class Client
 {
-    const LIBVER = "2.12.6";
+    // Release Please updates the VERSION constant. This workaround ensures the LIBVER constant
+    // will be updated for each release as well.
+    private const VERSION = '2.18.3';
+    const LIBVER = self::VERSION;
+
     const USER_AGENT_SUFFIX = "google-api-php-client/";
     const OAUTH2_REVOKE_URI = 'https://oauth2.googleapis.com/revoke';
     const OAUTH2_TOKEN_URI = 'https://oauth2.googleapis.com/token';
@@ -64,7 +68,7 @@ class Client
      */
     private $auth;
 
-    /**
+    **
      * @var ClientInterface $http
      */
     private $http;