Bump pgp plugin and remove extra matrix.

Running that extra matrix doesn't add anything to CI. I plan
on fully redoing the CI, but want to get this just released
first

Author: ckipp01

.github/workflows/pr.yml

@@ -14,8 +14,7 @@ jobs:
       matrix:
         java: [ '11' ]
         scala: [
-            { version: '2.12.13' },
-            { version: '2.12.10' }
+            { version: '2.12.13' }
           ]
     steps:
       - name: checkout the repo

project/plugins.sbt

@@ -1,6 +1,6 @@
 libraryDependencies += "org.scala-sbt" %% "scripted-plugin" % sbtVersion.value
 
-addSbtPlugin("com.jsuereth" % "sbt-pgp" % "1.1.0")
+addSbtPlugin("com.jsuereth" % "sbt-pgp" % "2.0.1")
 
 addSbtPlugin("org.scalariform" % "sbt-scalariform" % "1.8.1")