Refresh namespace runtime config and linux nix env

.forgejo/workflows/build-rust.yml

@@ -19,6 +19,9 @@ jobs:
     runs-on: namespace-profile-linux-medium
     env:
       CARGO_INCREMENTAL: 0
+      NIX_CONFIG: |
+        experimental-features = nix-command flakes
+        accept-flake-config = true
       RUSTC_WRAPPER: sccache
       SCCACHE_CACHE_SIZE: 20G
     steps:
@@ -44,6 +47,11 @@ jobs:
           echo "SCCACHE_DIR=${shared_root}/sccache" >> "${GITHUB_ENV}"
           echo "XDG_CACHE_HOME=${shared_root}/xdg" >> "${GITHUB_ENV}"
           echo "CARGO_TARGET_DIR=${lane_root}/cargo-target" >> "${GITHUB_ENV}"
+          {
+            echo 'NIX_CONFIG<<EOF'
+            printf '%s\n' "${NIX_CONFIG}"
+            echo 'EOF'
+          } >> "${GITHUB_ENV}"
           df -h /nix "${shared_root}" "${lane_root}" || true
 
       - name: Test