chore(web-app-template): Simplify adding to a map

The `+` operator has an overload for pairs as well.

Signed-off-by: Sebastian Schuberth <sebastian@doubleopen.org>

plugins/reporters/web-app-template/build.gradle.kts

@@ -61,7 +61,7 @@ tasks.addRule("Pattern: yarn<Command>") {
                 oldPath
             ).joinToString(File.pathSeparator)
 
-            environment = environment + mapOf("PATH" to newPath)
+            environment = environment + ("PATH" to newPath)
         }
     }
 }