Check build system formatting on CI

.github/workflows/main.yml

@@ -19,6 +19,7 @@ jobs:
     - name: Rustfmt
       run: |
         cargo fmt --check
+        rustfmt --check build_system/mod.rs
 
   build:
     runs-on: ${{ matrix.os }}
@@ -198,14 +199,14 @@ jobs:
 
         # Enable extra checks
         $Env:CG_CLIF_ENABLE_VERIFIER=1
-        
+
         # WIP Disable some tests
-        
+
         # This fails due to some weird argument handling by hyperfine, not an actual regression
         # more of a build system issue
         (Get-Content config.txt) -replace '(bench.simple-raytracer)', '# $1' |  Out-File config.txt
-        
-        # This fails with a different output than expected 
+
+        # This fails with a different output than expected
         (Get-Content config.txt) -replace '(test.regex-shootout-regex-dna)', '# $1' |  Out-File config.txt
 
         ./y.exe test