[Editorial] Update github workflows to use ubuntu-latest

This makes sure that we move onto a newer Python version, which
is required by bikesheds newer releases.

Author: stephenmcgruer

.github/workflows/auto-publish.yml

@@ -11,7 +11,7 @@ on:
 jobs:
   main:
     name: Build, Validate and Deploy
-    runs-on: ubuntu-20.04
+    runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v2
       - uses: w3c/spec-prod@v2
@@ -24,4 +24,4 @@ jobs:
           W3C_WG_DECISION_URL: https://www.w3.org/2016/04/14-wpwg-minutes.html
           W3C_BUILD_OVERRIDE: |
             status: CRD
-            shortname: secure-payment-confirmation
+            shortname: secure-payment-confirmation

.github/workflows/build.yml

@@ -7,7 +7,7 @@ on:
 jobs:
   main:
     name: Build, Validate, and Publish
-    runs-on: ubuntu-20.04
+    runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v2
       - uses: w3c/spec-prod@v2