chore: fix ubuntu version for docs generation (#2160)

Author: bshaffer

.github/workflows/docs.yml

@@ -9,7 +9,7 @@ on:
 jobs:
     docs:
         name: "Generate Project Documentation"
-        runs-on: ubuntu-16.04
+        runs-on: ubuntu-latest
         steps:
         - name: Checkout
           uses: actions/checkout@v2