Revert "Update FTL to newer version"

This reverts commit 9b7f605.

MI doesn't rely on the item part of FTL, so it will just work on any version.
Let's not introduce unnecessary compat issues for now.

gradle.properties

@@ -25,7 +25,7 @@ org.gradle.jvmargs=-Xmx1G
 	architectury_file=3218916
 	rhino_file=3187177
 	arrp_version=0.2.9
-	ftl_version=0.4.0-pre01
+	ftl_version=0.3.1
 	magna_version=1.5.1-1.16.5
 # Other mods for testing
 	appeng_version=8.1.0-alpha.12