Update Swatinem/rust-cache action to v2.8.1

Author: oxide-renovate[bot]

.github/workflows/ci.yml

@@ -21,7 +21,7 @@ jobs:
         with:
           components: rustfmt, clippy
       - uses: taiki-e/install-action@just
-      - uses: Swatinem/rust-cache@98c8021b550208e191a6a3145459bfc9fb29c4c0 # v2.8.0
+      - uses: Swatinem/rust-cache@f13886b937689c021905a6b90929199931d60db1 # v2.8.1
         with:
           key: partition-${{ matrix.partition }}
       - name: Lint (clippy)
@@ -53,7 +53,7 @@ jobs:
       - uses: dtolnay/rust-toolchain@master
         with:
           toolchain: ${{ matrix.rust-version }}
-      - uses: Swatinem/rust-cache@98c8021b550208e191a6a3145459bfc9fb29c4c0 # v2.8.0
+      - uses: Swatinem/rust-cache@f13886b937689c021905a6b90929199931d60db1 # v2.8.1
         with:
           key: partition-${{ matrix.partition }}
       - uses: taiki-e/install-action@nextest