use update instead of install for dependency installation

this is probably better considering a range of php versions

Author: EvaLok

.github/workflows/php-tests.yaml

@@ -20,7 +20,7 @@ jobs:
         php-version: ${{ matrix.php-version }}
 
     - name: Install dependencies
-      run: composer install --prefer-source --no-interaction --dev
+      run: composer update --prefer-source --no-interaction --dev
 
     - name: Run tests
       run: vendor/bin/phpspec run --no-interaction