Add Gson and lsp4j dependencies as required after last merge

tlatools/org.lamport.tlatools/build.gradle

@@ -13,6 +13,11 @@ repositories {
 	mavenCentral()
 }
 
+dependencies {
+	implementation(group: "com.google.code.gson", name: "gson", version: "2.8.6")
+	implementation(group: "org.eclipse.lsp4j", name: "org.eclipse.lsp4j.debug", version: "0.10.0")
+}
+
 sourceSets {
 	main {
 		java {