build!: Update rules_kotlin dep to 1.9.6. (#7)

BREAKING CHANGE: Kotlin language version updated to 2.0

MODULE.bazel

@@ -3,9 +3,9 @@ module(
     repo_name = "wfa_rules_kotlin_jvm",
 )
 
-KOTLIN_RELEASE_VERSION = "1.8.22"
+KOTLIN_RELEASE_VERSION = "2.0.0"  # Compatible with rules_kotlin version.
 
-KOTLINX_COROUTINES_VERSION = "1.7.3"
+KOTLINX_COROUTINES_VERSION = "1.8.1"
 
 GRPC_JAVA_VERSION = "1.60.2"
 
@@ -27,7 +27,7 @@ bazel_dep(
 )
 bazel_dep(
     name = "rules_kotlin",
-    version = "1.9.0",
+    version = "1.9.6",
 )
 bazel_dep(
     name = "rules_jvm_external",
@@ -82,3 +82,5 @@ http_file(
         version = GRPC_JAVA_VERSION,
     ),
 )
+
+register_toolchains("//kotlin:kotlin_toolchain")

kotlin/BUILD.bazel

@@ -1,4 +1,4 @@
-load("@rules_kotlin//kotlin:core.bzl", "kt_kotlinc_options")
+load("@rules_kotlin//kotlin:core.bzl", "define_kt_toolchain", "kt_kotlinc_options")
 
 package(default_visibility = ["//visibility:public"])
 
@@ -7,3 +7,9 @@ kt_kotlinc_options(
     include_stdlibs = "none",
     x_optin = ["kotlin.RequiresOptIn"],
 )
+
+define_kt_toolchain(
+    name = "kotlin_toolchain",
+    jvm_target = "11",
+    kotlinc_options = ":default_opts",
+)

kotlin/internal/library.bzl

@@ -28,7 +28,6 @@ def kt_jvm_library(
         name,
         deps = None,
         exports = None,
-        kotlinc_opts = Label("//kotlin:default_opts"),
         **kwargs):
     deps = deps or []
     exports = exports or []
@@ -37,6 +36,5 @@ def kt_jvm_library(
         name = name,
         deps = deps + _STDLIBS,
         exports = exports + _STDLIBS,
-        kotlinc_opts = kotlinc_opts,
         **kwargs
     )