Simplify lakefile a bit and rebuild

Author: utensil

.github/workflows/ci.yml

@@ -145,6 +145,7 @@ jobs:
       - name: Build GiNaC (Windows)
         if: runner.os == 'Windows'
         run: |
+          lake clean
           bash ./scripts/build_cln.sh
           bash ./scripts/build_ginac.sh
       - name: lake build

lakefile.lean

@@ -18,9 +18,6 @@ package «GinacLean» where
 
 lean_lib «GinacLean» where
   roots := #[`Ginac]
-  moreLinkArgs := #[s!"-L{__dir__}/.lake/build/lib",
-  "-lginac_ffi",
-  "-lstdc++"]
   extraDepTargets := #[`libginac_ffi]
 
 @[default_target]