Update linux-builds.yml

Updated actions/cache@v1 to actions/cache@v3

Author: githubuser0xFFFF

.github/workflows/linux-builds.yml

@@ -28,7 +28,7 @@ jobs:
     - uses: actions/checkout@v2
     - name: Cache Qt
       id: cache-qt-6-4
-      uses: actions/cache@v1  # not v2!
+      uses: actions/cache@v3
       with:
         path: ../Qt/6.4.2
         key: ${{ runner.os }}-QtCache-Qt6-4