chore(github-actions): improve ci cache (twilight-rs#1151)

I noticed that the cache used for the CI was inefficient: all dependencies are recompiled each time, which made the CI very long to run.

This PR replaces the existing cache with the [`Swatinem/rust-cache`](https://github.com/Swatinem/rust-cache/) action, that correctly cache dependencies. This cache is used in [other big projects](https://github.com/rust-analyzer/rust-analyzer/blob/b73b321478d3b2a98d380eb79de717e01620c4e9/.github/workflows/ci.yaml#L53-L54) like `rust-analyzer`.

Author: baptiste0928

.github/workflows/doc.yml

@@ -19,14 +19,8 @@ jobs:
           profile: minimal
           override: true
 
-      - name: Setup cache
-        uses: actions/cache@v2
-        with:
-          path: |
-            ~/.cargo/registry
-            ~/.cargo/git
-            target/debug
-          key: ${{ runner.os }}-docs-rustc-${{ steps.toolchain.outputs.rustc_hash }}-${{ hashFiles('**/Cargo.lock') }}
+      - name: Cache dependencies
+        uses: Swatinem/rust-cache@v1
 
       - name: Build docs
         env:

.github/workflows/lint.yml

@@ -20,14 +20,8 @@ jobs:
           profile: minimal
           override: true
 
-      - name: Setup cache
-        uses: actions/cache@v2
-        with:
-          path: |
-            ~/.cargo/registry
-            ~/.cargo/git
-            target
-          key: ${{ runner.os }}-clippy-rustc-${{ steps.toolchain.outputs.rustc_hash }}-${{ hashFiles('**/Cargo.lock') }}
+      - name: Cache dependencies
+        uses: Swatinem/rust-cache@v1
 
       - name: Run clippy
         uses: actions-rs/clippy-check@v1

.github/workflows/publish.yml

@@ -22,14 +22,8 @@ jobs:
           profile: minimal
           override: true
 
-      - name: Setup cache
-        uses: actions/cache@v2
-        with:
-          path: |
-            ~/.cargo/registry
-            ~/.cargo/git
-            target/debug
-          key: ${{ runner.os }}-docs-rustc-${{ steps.toolchain.outputs.rustc_hash }}-${{ hashFiles('**/Cargo.lock') }}
+      - name: Cache dependencies
+        uses: Swatinem/rust-cache@v1
 
       - name: Build docs
         env:

.github/workflows/test.yml

@@ -22,14 +22,8 @@ jobs:
           profile: minimal
           override: true
 
-      - name: Setup cache
-        uses: actions/cache@v2
-        with:
-          path: |
-            ~/.cargo/registry
-            ~/.cargo/git
-            target
-          key: ${{ runner.os }}-test-rustc-${{ steps.toolchain.outputs.rustc_hash }}-${{ hashFiles('**/Cargo.lock') }}
+      - name: Cache dependencies
+        uses: Swatinem/rust-cache@v1
 
       - name: Run cargo test
         run: cargo test
@@ -88,14 +82,8 @@ jobs:
           profile: minimal
           override: true
 
-      - name: Setup cache
-        uses: actions/cache@v2
-        with:
-          path: |
-            ~/.cargo/registry
-            ~/.cargo/git
-            target
-          key: ${{ runner.os }}-test-rustc-${{ steps.toolchain.outputs.rustc_hash }}-${{ hashFiles('**/Cargo.lock') }}
+      - name: Cache dependencies
+        uses: Swatinem/rust-cache@v1
 
       - name: Test ${{ matrix.package }} feat. ${{ matrix.features }}
         working-directory: ${{ matrix.package }}
@@ -119,14 +107,8 @@ jobs:
           profile: minimal
           override: true
 
-      - name: Setup cache
-        uses: actions/cache@v2
-        with:
-          path: |
-            ~/.cargo/registry
-            ~/.cargo/git
-            target
-          key: ${{ runner.os }}-msrv-${{ steps.tc.outputs.rustc_hash }}-${{ hashFiles('**/Cargo.lock') }}
+      - name: Cache dependencies
+        uses: Swatinem/rust-cache@v1
 
       - run: cargo check --examples --tests --all-features
         env: