Use ubuntu20.04 for GH action

Author: ljvmiranda921

.github/workflows/publish.yaml

@@ -1,20 +1,19 @@
 name: Publish
 on:
   push:
-    branches: 
+    branches:
       - master
 jobs:
   publish:
-    runs-on: ubuntu-18.04
+    runs-on: ubuntu-20.04
     steps:
       - uses: actions/checkout@v2
       - uses: docker://blang/latex:ubuntu
         with:
           args: latexmk -pdf -outdir=./_build
       - uses: google-github-actions/setup-gcloud@v0
         with:
-          version: '290.0.1'
+          version: "290.0.1"
           service_account_key: ${{ secrets.GCP_SA_KEY }}
           export_default_credentials: true
       - run: gsutil cp _build/LJMiranda_CV.pdf gs://ljvmiranda/cv.pdf
-