ci: use DeterminateSystems/determinate-nix-action

Author: TerrorJack

.github/workflows/ci.yml

@@ -14,7 +14,7 @@ jobs:
     steps:
       - uses: actions/checkout@v5
 
-      - uses: DeterminateSystems/nix-installer-action@v20
+      - uses: DeterminateSystems/determinate-nix-action@v3
 
       - uses: DeterminateSystems/magic-nix-cache-action@main
 

.github/workflows/mirror.yml

@@ -18,7 +18,7 @@ jobs:
     steps:
       - uses: actions/checkout@v5
 
-      - uses: DeterminateSystems/nix-installer-action@v20
+      - uses: DeterminateSystems/determinate-nix-action@v3
 
       - uses: DeterminateSystems/magic-nix-cache-action@main