fix: skip template lines to avoid parser errors

Fixes #26

src/common.ts

@@ -483,13 +483,28 @@ export function checkContributors(path: PathLike, packageJson: PackageJSON): voi
  * @param path Path to CI config
  */
 export function checkCIConfig(rules: Rules, path: string): void {
-// check CI config if it exists
   const pathToCiConfig = resolve(path, '.gitlab-ci.yml');
+
+  // check CI config if it exists
   if (existsSync(pathToCiConfig)) {
     // read CI config
-    const buffer = readFileSync(pathToCiConfig);
+    const content = readFileSync(pathToCiConfig)
+      .toString();
+
+    let ciConfigWithoutTemplates = '';
+
+    for (const line of content.split('\n')) {
+      const match = line
+        .trim()
+        .match(/^<</);
+
+      if (match === null) {
+        ciConfigWithoutTemplates += `${line}\n`;
+      }
+    }
+
     try {
-      const ciConfig = parse(buffer.toString());
+      const ciConfig = parse(ciConfigWithoutTemplates);
 
       // check entries
       for (const entry in rules.ciConfig) {