Run Gitea workflows on Ubuntu only

.gitea/workflows/imaging-meshing.yml

@@ -6,11 +6,7 @@ on:
 
 jobs:
   native:
-    strategy:
-      fail-fast: false
-      matrix:
-        os: [ubuntu-latest, macos-latest, windows-latest]
-    runs-on: ${{ matrix.os }}
+    runs-on: ubuntu-latest
     env:
       RUSTDOCFLAGS: -D warnings
     steps:
@@ -44,5 +40,4 @@ jobs:
           cargo clippy -p libremetaverse-imaging -p libremetaverse-imaging-skia -p libremetaverse-prim-mesher --all-targets -- -D warnings
           cargo doc -p libremetaverse-imaging -p libremetaverse-imaging-skia -p libremetaverse-prim-mesher --no-deps
       - name: Verify formatting
-        if: runner.os == 'Linux'
         run: cargo fmt --all -- --check