Enable cache sweeping in CI (#289)

Addresses part of #212.

I recently merged a feature into
[Leafwing-Studios/cargo-cache](https://github.com/Leafwing-Studios/cargo-cache)
v2.3.0 that automatically deletes unused build artifacts before creating
a new cache, to prevent cache sizes from snowballing.

It's disabled by default due to backward compatibility reasons, so this
PR enables it. Cache sweeping should keep cache sizes small and workflow
runs fast.

(As an side, should a cache be used at all in the release build? Caching
prevents builds from being reproducible, and can introduce the
occasional issue when building.)

.github/workflows/ci.yaml

@@ -29,6 +29,8 @@ jobs:
 
       - name: Populate target directory from cache
         uses: Leafwing-Studios/cargo-cache@v2
+        with:
+          sweep-cache: true
 
       - name: Run tests
         run: |
@@ -55,6 +57,8 @@ jobs:
 
       - name: Populate target directory from cache
         uses: Leafwing-Studios/cargo-cache@v2
+        with:
+          sweep-cache: true
 
       - name: Run clippy lints
         run: cargo clippy --workspace --all-targets --all-features -- --deny warnings
@@ -93,6 +97,8 @@ jobs:
 
       - name: Populate target directory from cache
         uses: Leafwing-Studios/cargo-cache@v2
+        with:
+          sweep-cache: true
 
       - name: Check documentation
         run: cargo doc --workspace --all-features --document-private-items --no-deps

.github/workflows/release.yaml

@@ -149,6 +149,8 @@ jobs:
 
       - name: Populate cargo cache
         uses: Leafwing-Studios/cargo-cache@v2
+        with:
+          sweep-cache: true
 
       - name: Install dependencies (Linux)
         if: ${{ matrix.platform == 'linux' }}