Bump version to 5.2.9

Signed-off-by: shedaniel <daniel@shedaniel.me>

gradle.properties

@@ -1,5 +1,5 @@
 org.gradle.jvmargs=-Xmx3G
-mod_version=5.2.8
+mod_version=5.2.9
 supported_version=1.16.2
 minecraft_version=1.16.2-rc1
 yarn_version=1.16.2-rc1+build.4+legacy.20w09a+build.8