Update sbt-github-actions to 0.26.0

Author: scala-steward

project/plugins.sbt

@@ -3,4 +3,4 @@ libraryDependencies += "org.scala-sbt" %% "scripted-plugin" % sbtVersion.value
 addSbtPlugin("com.github.sbt"    % "sbt-ci-release"     % "1.11.1")
 addSbtPlugin("de.heikoseeberger" % "sbt-header"         % "5.10.0")
 addSbtPlugin("org.scalameta"     % "sbt-scalafmt"       % "2.5.5")
-addSbtPlugin("com.github.sbt"    % "sbt-github-actions" % "0.25.0")
+addSbtPlugin("com.github.sbt"    % "sbt-github-actions" % "0.26.0")