Bump cachix/install-nix-action from 30 to 31 (#41)

Bumps [cachix/install-nix-action](https://github.com/cachix/install-nix-action) from 30 to 31.
- [Release notes](https://github.com/cachix/install-nix-action/releases)
- [Commits](https://github.com/cachix/install-nix-action/compare/v30...v31)

---
updated-dependencies:
- dependency-name: cachix/install-nix-action
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>
Co-authored-by: Patrick Stevens <3138005+Smaug123@users.noreply.github.com>

.github/workflows/dotnet.yaml

@@ -27,16 +27,17 @@ jobs:
     - uses: actions/checkout@v4
       with:
         fetch-depth: 0 # so that NerdBank.GitVersioning has access to history
-    - name: Setup .NET
-      uses: actions/setup-dotnet@v4
+    - name: Install Nix
+      uses: cachix/install-nix-action@v30
       with:
-        dotnet-version: 7.0.x
+        extra_nix_config: |
+          access-tokens = github.com=${{ secrets.GITHUB_TOKEN }}
     - name: Restore dependencies
-      run: dotnet restore
+      run: nix develop --command dotnet restore
     - name: Build
-      run: dotnet build --no-restore --configuration ${{matrix.config}}
+      run: nix develop --command dotnet build --no-restore --configuration ${{matrix.config}}
     - name: Test
-      run: dotnet test --no-build --verbosity normal --configuration ${{matrix.config}}
+      run: nix develop --command dotnet test --no-build --verbosity normal --configuration ${{matrix.config}}
 
   build-nix:
     runs-on: ubuntu-latest
@@ -44,7 +45,7 @@ jobs:
       - name: Checkout
         uses: actions/checkout@v4
       - name: Install Nix
-        uses: cachix/install-nix-action@v30
+        uses: cachix/install-nix-action@v31
         with:
           extra_nix_config: |
             access-tokens = github.com=${{ secrets.GITHUB_TOKEN }}
@@ -59,7 +60,7 @@ jobs:
       - name: Checkout
         uses: actions/checkout@v4
       - name: Install Nix
-        uses: cachix/install-nix-action@v30
+        uses: cachix/install-nix-action@v31
         with:
           extra_nix_config: |
             access-tokens = github.com=${{ secrets.GITHUB_TOKEN }}
@@ -72,7 +73,7 @@ jobs:
       - name: Checkout
         uses: actions/checkout@v4
       - name: Install Nix
-        uses: cachix/install-nix-action@v30
+        uses: cachix/install-nix-action@v31
         with:
           extra_nix_config: |
             access-tokens = github.com=${{ secrets.GITHUB_TOKEN }}
@@ -85,7 +86,7 @@ jobs:
     steps:
       - uses: actions/checkout@master
       - name: Install Nix
-        uses: cachix/install-nix-action@v30
+        uses: cachix/install-nix-action@v31
         with:
           extra_nix_config: |
             access-tokens = github.com=${{ secrets.GITHUB_TOKEN }}