Stop versioning composer.lock

`composer.lock` should only be versioned for projects, not for libraries.

Author: oliverklee

.github/workflows/ci.yml

@@ -65,7 +65,7 @@ jobs:
         uses: actions/cache@v1
         with:
           path: ~/.cache/composer
-          key: php${{ matrix.php-version }}-composer-${{ hashFiles('**/composer.lock') }}
+          key: php${{ matrix.php-version }}-composer-${{ hashFiles('**/composer.json') }}
           restore-keys: |
             php${{ matrix.php-version }}-composer-
 

.gitignore

@@ -1 +1,2 @@
-vendor/
+/composer.lock
+/vendor/