Upgrade actions/cache verison to latest due to deprecation.

Author: larf311

.github/workflows/CI.yml

@@ -30,7 +30,7 @@ jobs:
         with:
           version: ${{ matrix.version }}
           arch: ${{ matrix.arch }}
-      - uses: actions/cache@v2
+      - uses: actions/cache@v4
         env:
           cache-name: cache-artifacts
         with:

.github/workflows/JuliaNightly.yml

@@ -31,7 +31,7 @@ jobs:
         with:
           version: ${{ matrix.version }}
           arch: ${{ matrix.arch }}
-      - uses: actions/cache@v2
+      - uses: actions/cache@v4
         env:
           cache-name: cache-artifacts
         with: