ci: add rust-cache action

Author: Firestar99

.github/workflows/ci.yaml

@@ -38,6 +38,11 @@ jobs:
       - if: ${{ runner.os == 'Linux' }}
         name: Linux - Install native dependencies
         run: sudo apt install libwayland-cursor0 libxkbcommon-dev libwayland-dev
+      - uses: Swatinem/rust-cache@v2
+        with:
+          workspaces: |
+            .
+            tests/difftests/tests
       # just need a random command that forces the installation of rust-toolchain
       # figure out native target triple while we're at it
       - name: install rust-toolchain
@@ -96,6 +101,11 @@ jobs:
           install_runtime: true
           cache: true
           stripdown: true
+      - uses: Swatinem/rust-cache@v2
+        with:
+          workspaces: |
+            .
+            tests/difftests/tests
       - name: install rust-toolchain
         run: cargo version
       - name: cargo fetch --locked
@@ -140,6 +150,11 @@ jobs:
           install_runtime: true
           cache: true
           stripdown: true
+      - uses: Swatinem/rust-cache@v2
+        with:
+          workspaces: |
+            .
+            tests/difftests/tests
       - name: install rust-toolchain
         run: echo "TARGET=$(rustc --print host-tuple)" >> "$GITHUB_ENV"
       - name: cargo fetch --locked
@@ -175,6 +190,11 @@ jobs:
           sudo add-apt-repository ppa:kisak/turtle -y
           sudo apt-get update
           sudo apt install -y xvfb libgl1-mesa-dri libxcb-xfixes0-dev mesa-vulkan-drivers
+      - uses: Swatinem/rust-cache@v2
+        with:
+          workspaces: |
+            .
+            tests/difftests/tests
       - name: install rust-toolchain
         run: echo "TARGET=$(rustc --print host-tuple)" >> "$GITHUB_ENV"
       - name: cargo fetch --locked
@@ -223,6 +243,11 @@ jobs:
           install_runtime: true
           cache: true
           stripdown: true
+      - uses: Swatinem/rust-cache@v2
+        with:
+          workspaces: |
+            .
+            tests/difftests/tests
       # cargo version is a random command that forces the installation of rust-toolchain
       - name: install rust-toolchain
         run: cargo version