Simplify build.zig to use upstream webui C library building (#70)

* scm: Use `webui`'s `build.zig` for building C lib

* scm: Update for latest `webui` `build.zig`

* scm: Update to latest upstream, drop 0.11.0

Author: mochalins

.github/workflows/ci.yml

@@ -19,7 +19,7 @@ jobs:
     strategy:
       matrix:
         os: [ubuntu-latest, macos-latest, windows-latest]
-        version: [0.11.0, 0.12.0, 0.13.0, ""]
+        version: [0.12.0, 0.13.0, ""]
       fail-fast: false
     runs-on: ${{ matrix.os }}
     steps: