Remove ubuntu18 as rules_proto absiel version doesn't support it

.bazelci/presubmit.yml

@@ -2,10 +2,8 @@
 matrix:
   unittest_platform:
     - ubuntu2004
-    - ubuntu1804
   integration_platform:
     - ubuntu2004
-    - ubuntu1804
     # - macos
     # - windows re-enable when rules_bazel_integration_test can support custom test runner on windows.
   test_flags:
@@ -35,7 +33,8 @@ tasks:
       - "--config=rbe"
     test_targets:
       - //examples:all
-  rbe_ubuntu1604:
+  rbe:
+    platform: ${{ unittest_platform }}
     test_targets:
       - "--"
       - "//src/test/kotlin/io/bazel/kotlin/builder:builder_tests"
@@ -50,7 +49,7 @@ tasks:
       - "--strategy=KotlinCompile=remote"
   stardoc:
     name: Stardoc api documentation
-    platform: ubuntu1804
+    platform: ubuntu2004
     build_flags:
       - "--enable_bzlmod=true"
     build_targets:
@@ -59,7 +58,7 @@ tasks:
       - //docs:are_docs_up_to_date_test
   ktlint:
     name: KtLint
-    platform: ubuntu1804
+    platform: ubuntu2004
     test_targets:
       - //...
     test_flags:

MODULE.bazel

@@ -99,8 +99,8 @@ maven.override(
 use_repo(maven, "kotlin_rules_maven", "unpinned_kotlin_rules_maven")
 
 bazel_dep(name = "rules_pkg", version = "1.0.1")
+bazel_dep(name = "rules_proto", version = "7.0.2")
 bazel_dep(name = "stardoc", version = "0.7.2", repo_name = "io_bazel_stardoc")
-bazel_dep(name = "rules_proto", version = "5.3.0-21.7")
 
 bazel_dep(name = "rules_testing", version = "0.5.0", dev_dependency = True)
 bazel_dep(name = "rules_bazel_integration_test", version = "0.25.0", dev_dependency = True)