Fix path executables not found on windows

Author: Ariouz

ci/python-gate.libsonnet

@@ -158,7 +158,7 @@
         },
         windows: {
             common: {
-                PATH: "$MAVEN_HOME\\bin;$PATH",
+                PATH: "%MAVEN_HOME%\\bin;%PATH%",
                 # Gradle: this feature doesn't work on all Windows CI machines
                 GRADLE_OPTS: "-Dorg.gradle.vfs.watch=false",
             },