Adjust nightly build (#3978)

Summary:
Fixes disk space issue: 75 GB -> 150 GB

https://www.internalfb.com/intern/opensource/ci/github-actions/runners/

S460776

Pull Request resolved: https://github.com/facebookresearch/faiss/pull/3978

Reviewed By: junjieqi

Differential Revision: D64722810

Pulled By: asadoughi

fbshipit-source-id: 0ae0f50e86bb0e8c19caa651a9dc496ebf700256

.github/workflows/nightly.yml

@@ -8,7 +8,7 @@ env:
 jobs:
   linux-x86_64-nightly:
     name: Linux x86_64 nightlies
-    runs-on: ubuntu-latest
+    runs-on: 4-core-ubuntu
     steps:
       - name: Checkout
         uses: actions/checkout@v4