Update ci_cd.yml to use ubuntu-latest runner in public branch

Author: nbehrens-bz

.github/workflows/ci_cd.yml

@@ -22,7 +22,7 @@ env:
 
 jobs:
   build:
-    runs-on: self-hosted
+    runs-on: ${{ github.repository == 'Backblaze/b2-sdk-java-private' && self-hosted || ubuntu-latest }}
     steps:
       - uses: actions/checkout@v4
         with: