Reduce core count for CI

.gitea/workflows/ci.yaml

@@ -10,7 +10,7 @@ jobs:
     runs-on: ubuntu-22.04
     steps:
       - uses: actions/checkout@v4
-      - uses: cachix/install-nix-action@v23
+      - uses: cachix/install-nix-action@v27
         with:
           # Gitea will supply a token in GITHUB_TOKEN, which this action will
           # try to pass to Nix when downloading from GitHub
@@ -18,6 +18,8 @@ jobs:
           extra_nix_config: |
             # Make sure we're using sandbox
             sandbox-fallback = false
+            # Big C++ projects fill up memory...
+            cores = 6
 
             extra-substituters = https://nix-cache.nul.ie/main
             extra-trusted-public-keys = main:mMChkG8LwXrFirVfudqjSHasK1jV31OVElYD3eImYl8=

.gitea/workflows/installer.yaml

@@ -14,7 +14,7 @@ jobs:
         uses: https://github.com/actions/setup-go@v4
         with:
           go-version: '>=1.20.1'
-      - uses: cachix/install-nix-action@v23
+      - uses: cachix/install-nix-action@v27
         with:
           github_access_token: ${{ secrets.GH_PULL_TOKEN }}
           extra_nix_config: |