ci: bump all actions versions

This is a backport of all of the GitHub Action versions from `master` as
of 07b2c41d2d.

* peaceiris/actions-gh-pages: v3 -> v4

  Release: https://github.com/peaceiris/actions-gh-pages/releases/tag/v4.0.0

* actions/labeler: v4 -> v5

  Release: https://github.com/actions/labeler/releases/tag/v5.0.0

* DeterminateSystems/update-flake-lock: v21 -> v22

  Release: https://github.com/DeterminateSystems/update-flake-lock/releases/tag/v22

Also used lowercase `v` for cachix/install-nix-action.

Signed-off-by: Sumner Evans <me@sumnerevans.com>

.github/workflows/github_pages.yml

@@ -11,7 +11,7 @@ jobs:
     runs-on: ${{ matrix.os }}
     steps:
     - uses: actions/checkout@v4
-    - uses: cachix/install-nix-action@V27
+    - uses: cachix/install-nix-action@v27
       with:
         nix_path: nixpkgs=channel:nixos-unstable
     - uses: cachix/cachix-action@v15
@@ -22,7 +22,7 @@ jobs:
         nix-build -A docs.html
         cp -r result/share/doc/home-manager public
     - name: Deploy
-      uses: peaceiris/actions-gh-pages@v3
+      uses: peaceiris/actions-gh-pages@v4
       with:
         github_token: ${{ secrets.GITHUB_TOKEN }}
         publish_dir: ./public

.github/workflows/labeler.yml

@@ -17,8 +17,7 @@ jobs:
     runs-on: ubuntu-latest
     if: github.repository_owner == 'nix-community'
     steps:
-      - uses: actions/labeler@v4
+      - uses: actions/labeler@v5
         with:
           repo-token: ${{ secrets.GITHUB_TOKEN }}
           sync-labels: true
-

.github/workflows/test.yml

@@ -12,7 +12,7 @@ jobs:
     runs-on: ${{ matrix.os }}
     steps:
     - uses: actions/checkout@v4
-    - uses: cachix/install-nix-action@V27
+    - uses: cachix/install-nix-action@v27
       with:
         nix_path: nixpkgs=channel:nixos-23.11
     - uses: cachix/cachix-action@v15

.github/workflows/update-flake.yml

@@ -12,9 +12,9 @@ jobs:
       - name: Checkout repository
         uses: actions/checkout@v4
       - name: Install Nix
-        uses: cachix/install-nix-action@V27
+        uses: cachix/install-nix-action@v27
       - name: Update flake.lock
-        uses: DeterminateSystems/update-flake-lock@v21
+        uses: DeterminateSystems/update-flake-lock@v22
         with:
           token: ${{ secrets.GH_TOKEN_FOR_UPDATES }}
           pr-labels: dependencies