Update ramsey/composer-install action to v4 (#97)

| datasource  | package                 | from  | to    |
| ----------- | ----------------------- | ----- | ----- |
| github-tags | ramsey/composer-install | 3.0.0 | 4.0.0 |

Co-authored-by: renovate[bot] <29139614+renovate[bot]@users.noreply.github.com>

Author: renovate[bot]

.github/workflows/ci.yml

@@ -47,7 +47,7 @@ jobs:
           coverage: "pcov"
           php-version: "${{ matrix.php-version }}"
           ini-values: "${{ env.INI_VALUES }}"
-      - uses: "ramsey/composer-install@v3"
+      - uses: "ramsey/composer-install@v4"
         with:
           composer-options: "--ignore-platform-req=php"
 
@@ -70,7 +70,7 @@ jobs:
           coverage: "pcov"
           php-version: "${{ matrix.php-version }}"
           ini-values: "${{ env.INI_VALUES }}"
-      - uses: "ramsey/composer-install@v3"
+      - uses: "ramsey/composer-install@v4"
         with:
           composer-options: "--ignore-platform-req=php"
 
@@ -100,7 +100,7 @@ jobs:
           coverage: "none"
           php-version: "${{ matrix.php-version }}"
           ini-values: "${{ env.INI_VALUES }}"
-      - uses: "ramsey/composer-install@v3"
+      - uses: "ramsey/composer-install@v4"
         with:
           composer-options: "--ignore-platform-req=php"
 
@@ -122,7 +122,7 @@ jobs:
           coverage: "none"
           php-version: "${{ matrix.php-version }}"
           ini-values: "${{ env.INI_VALUES }}"
-      - uses: "ramsey/composer-install@v3"
+      - uses: "ramsey/composer-install@v4"
         with:
           composer-options: "--ignore-platform-req=php"