Bump actions/cache from 4 to 5

Bumps [actions/cache](https://github.com/actions/cache) from 4 to 5.
- [Release notes](https://github.com/actions/cache/releases)
- [Changelog](https://github.com/actions/cache/blob/main/RELEASES.md)
- [Commits](https://github.com/actions/cache/compare/v4...v5)

---
updated-dependencies:
- dependency-name: actions/cache
  dependency-version: '5'
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <support@github.com>

.github/workflows/nightly-linux.yml

@@ -15,7 +15,7 @@ jobs:
 
     - name: Cargo-C Toolchain Cache
       id: linux-cargo-c-toolchain
-      uses: actions/cache@v4
+      uses: actions/cache@v5
       with:
         path: |
           ~/.cargo/bin/cargo-capi

.github/workflows/nightly-mac.yml

@@ -18,14 +18,14 @@ jobs:
 
     - name: Toolchain Cache
       id: mac-toolchain
-      uses: actions/cache@v4
+      uses: actions/cache@v5
       with:
         path: ~/mac-toolchain
         key: ${{ runner.os }}-${{ runner.arch }}-toolchain
 
     - name: Cargo-C Toolchain Cache
       id: mac-cargo-c-toolchain
-      uses: actions/cache@v4
+      uses: actions/cache@v5
       with:
         path: |
           ~/.cargo/bin/cargo-capi

.github/workflows/nightly-win.yml

@@ -142,7 +142,7 @@ jobs:
 
     - name: Cargo-C Toolchain Cache
       id: windows-cargo-c-toolchain
-      uses: actions/cache@v4
+      uses: actions/cache@v5
       with:
         path: |
           ~/.cargo/bin/cargo-capi