Add separate fetch task and caching

Signed-off-by: trivernis <trivernis@protonmail.com>

.github/workflows/test.yml

@@ -16,6 +16,20 @@ jobs:
       - uses: actions/checkout@v2
         if: ${{ !env.ACT }}
 
+      - name: Cache build data
+        if: ${{ !env.ACT }}
+        uses: actions/cache@v2
+        with:
+          path: |
+            target
+            ~/.cargo/
+          key: ${{ runner.os }}-cargo-${{ hashFiles('Cargo.lock') }}
+          restore-keys: |
+            ${{ runner.os }}-cargo-
+
+      - name: Fetch
+        run: cargo fetch
+
       - name: Check
         run: cargo check --all-features