Use the ramsey/composer-install action to install dependencies

Like doctrine/.github#16

.github/workflows/continuous-integration.yml

@@ -21,9 +21,9 @@ jobs:
           - "7.4"
           - "8.0"
         deps:
-          - "normal"
+          - "highest"
         include:
-          - deps: "low"
+          - deps: "lowest"
             php-version: "7.1"
 
     steps:
@@ -46,31 +46,10 @@ jobs:
           php-version: "${{ matrix.php-version }}"
           coverage: "xdebug"
 
-      - name: "Cache dependencies installed with composer"
-        uses: "actions/cache@v2"
+      - name: "Install dependencies with Composer"
+        uses: "ramsey/composer-install@v1"
         with:
-          path: "~/.composer/cache"
-          key: "php-${{ matrix.php-version }}-composer-locked-${{ hashFiles('composer.lock') }}"
-          restore-keys: "php-${{ matrix.php-version }}-composer-locked-"
-
-      # Remove this block when
-      # https://github.com/felixfbecker/php-language-server-protocol/pull/15 is
-      # merged and released
-      - name: "Remove dependency on vimeo/psalm for PHP8"
-        run: "composer remove --dev --no-update vimeo/psalm"
-        if: "${{ matrix.php-version == '8.0' }}"
-
-      - name: "Downgrade Composer"
-        run: "composer self-update --1"
-        if: "${{ matrix.php-version == '7.1' }}"
-
-      - name: "Update dependencies with composer"
-        run: "composer update --no-interaction --no-progress --no-suggest"
-        if: "${{ matrix.deps == 'normal' }}"
-
-      - name: "Install lowest possible dependencies with composer"
-        run: "composer update --no-interaction --no-progress --no-suggest --prefer-dist --prefer-lowest"
-        if: "${{ matrix.deps == 'low' }}"
+          dependency-versions: "${{ matrix.deps }}"
 
       - name: "Run PHPUnit"
         run: "vendor/bin/phpunit --coverage-clover=coverage.xml"