Update sbt-pgp to 2.2.1 (#305)

Author: scala-steward

project/plugins.sbt

@@ -1,7 +1,7 @@
 addSbtPlugin("org.scalameta" % "sbt-scalafmt" % "2.5.0")
 addSbtPlugin("de.heikoseeberger" % "sbt-header" % "5.9.0")
 addSbtPlugin("com.github.sbt" % "sbt-release" % "1.1.0")
-addSbtPlugin("com.github.sbt" % "sbt-pgp" % "2.2.0")
+addSbtPlugin("com.github.sbt" % "sbt-pgp" % "2.2.1")
 addSbtPlugin("org.xerial.sbt" % "sbt-sonatype" % "3.9.15")
 addSbtPlugin("com.47deg" % "sbt-microsites" % "1.4.0")
 addSbtPlugin("org.scalameta" % "sbt-mdoc" % "2.3.6")