ci: fix cache (#46)

Author: astrainfinita

.github/workflows/build.yml

@@ -74,9 +74,7 @@ jobs:
         run: |
           rm -rf .lake/build/lib/Mutable/
           rm -rf .lake/build/lib/Algorithm/
-          # Fail quickly if the cache is completely cold, by checking for Mathlib.Init
-          lake exe cache get Mathlib.Init
-          lake build --no-build Mathlib.Init && lake exe cache get || echo "No cache for 'Mathlib.Init' available"
+          lake exe cache get
 
       - name: update {Mutable, Algorithm}.lean
         id: mk_all