Bump actions/cache from 4 to 6

Bumps [actions/cache](https://github.com/actions/cache) from 4 to 6.
- [Release notes](https://github.com/actions/cache/releases)
- [Changelog](https://github.com/actions/cache/blob/main/RELEASES.md)
- [Commits](actions/cache@v4...v6)

---
updated-dependencies:
- dependency-name: actions/cache
  dependency-version: '6'
  dependency-type: direct:production
  update-type: version-update:semver-major
...

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

Author: dependabot[bot]

.github/workflows/bazel_build.yml

@@ -13,7 +13,7 @@ jobs:
       - uses: actions/checkout@v6
 
       - name: Mount bazel cache
-        uses: actions/cache@v4
+        uses: actions/cache@v6
         with:
           path: "/home/runner/.cache/bazel"
           key: bazel
@@ -50,7 +50,7 @@ jobs:
       - uses: actions/checkout@v6
 
       - name: Mount bazel cache
-        uses: actions/cache@v4
+        uses: actions/cache@v6
         with:
           path: "/home/runner/.cache/bazel"
           key: bazel
@@ -87,7 +87,7 @@ jobs:
     - uses: actions/checkout@v6
 
     - name: Mount bazel cache
-      uses: actions/cache@v4
+      uses: actions/cache@v6
       with:
         path: "/home/runner/.cache/bazel"
         key: bazel-ubuntu22
@@ -110,7 +110,7 @@ jobs:
     - uses: actions/checkout@v6
 
     - name: Mount bazel cache
-      uses: actions/cache@v4
+      uses: actions/cache@v6
       with:
         path: "/home/runner/.cache/bazel"
         key: bazel-ubuntu24
@@ -133,7 +133,7 @@ jobs:
     - uses: actions/checkout@v6
 
     - name: Mount bazel cache
-      uses: actions/cache@v4
+      uses: actions/cache@v6
       with:
         path: "/home/runner/.cache/bazel"
         key: bazel
@@ -156,7 +156,7 @@ jobs:
     - uses: actions/checkout@v6
 
     - name: Mount bazel cache
-      uses: actions/cache@v4
+      uses: actions/cache@v6
       with:
         path: "/home/runner/.cache/bazel"
         key: bazel