Resolve "Support for IntelliJ 2021.3"

Closes #18 (closed)

gradle.properties

@@ -8,14 +8,14 @@ pluginVersion = 0.3.0
 # See https://plugins.jetbrains.com/docs/intellij/build-number-ranges.html
 # for insight into build numbers and IntelliJ Platform versions.
 pluginSinceBuild = 211
-pluginUntilBuild = 212.*
+pluginUntilBuild = 213.*
 
 # Plugin Verifier integration -> https://github.com/JetBrains/gradle-intellij-plugin#plugin-verifier-dsl
 # See https://jb.gg/intellij-platform-builds-list for available build versions.
-pluginVerifierIdeVersions = 2021.1.1, 2021.1.2, 2021.1.3, 2021.2.3
+pluginVerifierIdeVersions = 2021.1.1, 2021.1.2, 2021.1.3, 2021.2.3, 2021.3.1
 
 platformType = IC
-platformVersion = 2021.2.3
+platformVersion = 2021.3.1
 platformDownloadSources = true
 
 # Plugin Dependencies -> https://plugins.jetbrains.com/docs/intellij/plugin-dependencies.html