Bump GH action version

Author: valeriansaliou

.github/workflows/build.yml

@@ -15,7 +15,7 @@ jobs:
 
       - name: Cache build artifacts
         id: cache-cargo
-        uses: actions/cache@v2
+        uses: actions/cache@v4
         with:
           path: |
             ~/.cargo/bin

.github/workflows/test.yml

@@ -18,7 +18,7 @@ jobs:
 
       - name: Cache build artifacts
         id: cache-cargo
-        uses: actions/cache@v2
+        uses: actions/cache@v4
         with:
           path: |
             ~/.cargo/registry