Update actions/cache action to v4

| datasource  | package       | from | to |
| ----------- | ------------- | ---- | -- |
| github-tags | actions/cache | v3   | v4 |

Author: renovate[bot]

.github/workflows/benchmarks.yml

@@ -32,7 +32,7 @@ jobs:
           tools: composer:v2, cs2pr
 
       - name: "Cache dependencies"
-        uses: "actions/cache@v3"
+        uses: "actions/cache@v4"
         with:
           path: |
             ~/.composer/cache

.github/workflows/coding-standards.yml

@@ -32,7 +32,7 @@ jobs:
           tools: composer:v2, cs2pr
 
       - name: "Cache dependencies"
-        uses: "actions/cache@v3"
+        uses: "actions/cache@v4"
         with:
           path: |
             ~/.composer/cache

.github/workflows/demo-scripts.yml

@@ -32,7 +32,7 @@ jobs:
           tools: composer:v2, cs2pr
 
       - name: "Cache dependencies"
-        uses: "actions/cache@v3"
+        uses: "actions/cache@v4"
         with:
           path: |
             ~/.composer/cache

.github/workflows/mutation-tests.yml

@@ -32,7 +32,7 @@ jobs:
           tools: composer:v2, cs2pr
 
       - name: "Cache dependencies"
-        uses: "actions/cache@v3"
+        uses: "actions/cache@v4"
         with:
           path: |
             ~/.composer/cache

.github/workflows/phpunit.yml

@@ -38,7 +38,7 @@ jobs:
           tools: composer:v2, cs2pr
 
       - name: "Cache dependencies"
-        uses: "actions/cache@v3"
+        uses: "actions/cache@v4"
         with:
           path: |
             ~/.composer/cache

.github/workflows/psalm.yml

@@ -32,7 +32,7 @@ jobs:
           tools: composer:v2, cs2pr
 
       - name: "Cache dependencies"
-        uses: "actions/cache@v3"
+        uses: "actions/cache@v4"
         with:
           path: |
             ~/.composer/cache