Update sbt-github-actions to 0.26.0

Author: scala-steward

project/plugins.sbt

@@ -2,4 +2,4 @@ addSbtPlugin("de.heikoseeberger" % "sbt-header" % "5.10.0")
 addSbtPlugin("net.virtual-void" % "sbt-dependency-graph" % "0.9.2")
 addSbtPlugin("com.jsuereth" % "sbt-pgp" % "1.1.1")
 addSbtPlugin("com.github.gseitz" % "sbt-release" % "1.0.10")
-addSbtPlugin("com.github.sbt" % "sbt-github-actions" % "0.15.0")
+addSbtPlugin("com.github.sbt" % "sbt-github-actions" % "0.26.0")