Update .gitattributes

Author: malczuuu

.gitattributes

@@ -5,6 +5,15 @@
 # --- Java source files ---
 *.java     text diff=java
 
+# --- Kotlin source files ---
+*.kt       text diff=kotlin
+*.kts      text diff=kotlin
+
+# --- Groovy source files ---
+*.groovy     text diff=groovy
+*.gsh        text
+*.groovy.kts text
+
 # --- Gradle files ---
 *.gradle   text
 *.gradle.kts text