chore(deps): bump actions/cache from 4 to 6

.github/workflows/ci.yml

@@ -32,7 +32,7 @@ jobs:
       # database - not something a CI runner has; see its own failure message:
       # "Run 'dotnet run -- --auth' from src/selftest to authenticate").
       - name: Restore NuGet cache
-        uses: actions/cache@v4
+        uses: actions/cache@v6
         with:
           key: nuget-cache-${{ hashFiles('**/Directory.Packages.props', '**/*.csproj') }}
           path: ~/.nuget/packages

.github/workflows/codeql.yml

@@ -47,7 +47,7 @@ jobs:
       # ci.yml for why; CodeQL doesn't need the MAUI Windows target analyzed
       # separately from what the cross-platform library/test projects cover.
       - name: Restore NuGet cache
-        uses: actions/cache@v4
+        uses: actions/cache@v6
         with:
           key: nuget-cache-${{ hashFiles('**/Directory.Packages.props', '**/*.csproj') }}
           path: ~/.nuget/packages

.github/workflows/release-installers.yml

@@ -35,7 +35,7 @@ jobs:
         with:
           dotnet-version: 10.0.x
       - name: Restore NuGet cache
-        uses: actions/cache@v4
+        uses: actions/cache@v6
         with:
           key: nuget-cache-${{ hashFiles('**/Directory.Packages.props', '**/*.csproj') }}
           path: ~/.nuget/packages