chore(deps): update actions/checkout action to v6

.github/workflows/backport.yml

@@ -21,7 +21,7 @@ jobs:
     if: github.repository_owner == 'PrismLauncher' && github.event.pull_request.merged == true && (github.event_name != 'labeled' || startsWith('backport', github.event.label.name))
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
         with:
           ref: ${{ github.event.pull_request.head.sha }}
       - name: Create backport PRs

.github/workflows/build.yml

@@ -139,7 +139,7 @@ jobs:
       ##
 
       - name: Checkout
-        uses: actions/checkout@v5
+        uses: actions/checkout@v6
         with:
           submodules: true
 

.github/workflows/codeql.yml

@@ -60,7 +60,7 @@ jobs:
 
     steps:
       - name: Checkout repository
-        uses: actions/checkout@v5
+        uses: actions/checkout@v6
         with:
           submodules: "true"
 

.github/workflows/flatpak.yml

@@ -84,7 +84,7 @@ jobs:
 
     steps:
       - name: Checkout repository
-        uses: actions/checkout@v5
+        uses: actions/checkout@v6
         with:
           submodules: true
 

.github/workflows/nix.yml

@@ -92,7 +92,7 @@ jobs:
 
     steps:
       - name: Checkout repository
-        uses: actions/checkout@v5
+        uses: actions/checkout@v6
 
       - name: Install Nix
         uses: cachix/install-nix-action@v31

.github/workflows/release.yml

@@ -20,7 +20,7 @@ jobs:
       upload_url: ${{ steps.create_release.outputs.upload_url }}
     steps:
       - name: Checkout
-        uses: actions/checkout@v5
+        uses: actions/checkout@v6
         with:
           submodules: "true"
           path: "PrismLauncher-source"

.github/workflows/update-flake.yml

@@ -16,7 +16,7 @@ jobs:
     runs-on: ubuntu-latest
 
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
       - uses: cachix/install-nix-action@0b0e072294b088b73964f1d72dfdac0951439dbd # v31
 
       - uses: DeterminateSystems/update-flake-lock@v27