[rubygems/rubygems] newgem templ: Avoid Float 3.0 -> "3" in GH Action

This change avoids a YAML Float-to-String conversion, which turns a 3.0 into a "3". That can make names of builds less clear.

In order to use this new capability, I added a "name" descriptor to the matrix-created Job.

https://github.com/rubygems/rubygems/commit/6221241ad4

lib/bundler/templates/newgem/github/workflows/main.yml.tt

@@ -10,11 +10,11 @@ on:
 jobs:
   build:
     runs-on: ubuntu-latest
-
+    name: Ruby ${{ matrix.ruby }} 
     strategy:
       matrix:
         ruby:
-          - <%= RUBY_VERSION %>
+          - '<%= RUBY_VERSION %>'
 
     steps:
     - uses: actions/checkout@v2