.github/workflows/test.yml: bump checkout and cache actions to v4

Author: zozlak

.github/workflows/test.yml

@@ -6,8 +6,8 @@ jobs:
   phpunit:
     runs-on: ubuntu-latest
     steps:
-    - uses: actions/checkout@v2
-    - uses: actions/cache@v2
+    - uses: actions/checkout@v4
+    - uses: actions/cache@v4
       with: 
         path: vendor
         key: ${{ runner.os }}-composer-${{ hashFiles('**/composer.lock') }}
@@ -34,8 +34,8 @@ jobs:
   phpstan:
     runs-on: ubuntu-latest
     steps:
-    - uses: actions/checkout@v2
-    - uses: actions/cache@v2
+    - uses: actions/checkout@v4
+    - uses: actions/cache@v4
       with:
         path: vendor
         key: ${{ runner.os }}-composer-${{ hashFiles('**/composer.lock') }}