github-actions: only push to cache for main branch, update actions

Author: katrinafyi

.github/workflows/main.yml

@@ -13,10 +13,10 @@ jobs:
   update-check:
     runs-on: ubuntu-latest
     steps:
-    - uses: actions/checkout@v3
-    - uses: cachix/install-nix-action@v20
-    - run: |
-        nix run .#update -- check
+    - uses: actions/checkout@v4
+    - uses: cachix/install-nix-action@v25
+    - run: nix build .#update
+    - run: nix run .#update -- check
 
   build:
     strategy:
@@ -27,14 +27,14 @@ jobs:
           [aslp, bap-aslp, bap-primus, basil,
           alive2, retdec-uq-pac, asl-translator,
           gtirb-semantics, ddisasm, 
-          ocamlPackages_pac_4_09.asli]
+          ocamlPackages_pac_4_09.asli,
+          retdec5, remill]
     runs-on: ubuntu-latest
     steps:
-    - uses: actions/checkout@v3
-    - uses: cachix/install-nix-action@v20
-      with: { nix_path: 'nixpkgs=channel:nixpkgs-unstable' }
-    - uses: cachix/cachix-action@v12
-      with: { name: pac-nix, authToken: '${{ secrets.CACHIX_AUTH_TOKEN }}' }
+    - uses: actions/checkout@v4
+    - uses: cachix/install-nix-action@v25
+    - uses: cachix/cachix-action@v14
+      with: { name: pac-nix, authToken: '${{ secrets.CACHIX_AUTH_TOKEN }}', skipPush: "${{ github.ref != 'refs/heads/main' }}" }
 
     - run: nix build .#${{matrix.pkg}}
     - name: Run nix build .#${{matrix.pkg}}.tests