chore: Bazel 9 is rc now (#3394)

Work towards #3392

---------

Co-authored-by: Ignas Anikevicius <240938+aignas@users.noreply.github.com>

MODULE.bazel

diff --git a/MODULE.bazel b/MODULE.bazel
index 5854595..6e9b725 100644
--- a/MODULE.bazel
+++ b/MODULE.bazel
@@ -359,10 +359,7 @@
 )
 bazel_binaries.download(version = "7.4.1")
 bazel_binaries.download(version = "8.0.0")
-
-# For now, don't test with rolling, because that's Bazel 9, which is a ways
-# away.
-# bazel_binaries.download(version = "rolling")
+bazel_binaries.download(version = "9.0.0rc1")
 use_repo(
     bazel_binaries,
     "bazel_binaries",
@@ -371,6 +368,7 @@
     "bazel_binaries_bazelisk",
     "build_bazel_bazel_7_4_1",
     "build_bazel_bazel_8_0_0",
+    "build_bazel_bazel_9_0_0rc1",
     # "build_bazel_bazel_rolling",
     "build_bazel_bazel_self",
 )

tests/integration/BUILD.bazel

diff --git a/tests/integration/BUILD.bazel b/tests/integration/BUILD.bazel
index df7fe15..0e47faf 100644
--- a/tests/integration/BUILD.bazel
+++ b/tests/integration/BUILD.bazel
@@ -12,7 +12,6 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-load("@bazel_binaries//:defs.bzl", "bazel_binaries")
 load("@rules_bazel_integration_test//bazel_integration_test:defs.bzl", "default_test_runner")
 load("//python:py_library.bzl", "py_library")
 load(":integration_test.bzl", "rules_python_integration_test")
@@ -78,31 +77,33 @@
 
 rules_python_integration_test(
     name = "ignore_root_user_error_test",
+    env = {
+        "RULES_PYTHON_BZLMOD_DEBUG": "1",
+    },
 )
 
 rules_python_integration_test(
     name = "ignore_root_user_error_workspace_test",
     bzlmod = False,
+    env = {
+        "RULES_PYTHON_BZLMOD_DEBUG": "1",
+    },
     workspace_path = "ignore_root_user_error",
 )
 
 rules_python_integration_test(
     name = "local_toolchains_test",
-    bazel_versions = [
-        version
-        for version in bazel_binaries.versions.all
-        if not version.startswith("6.")
-    ],
+    env = {
+        "RULES_PYTHON_BZLMOD_DEBUG": "1",
+    },
 )
 
 rules_python_integration_test(
     name = "local_toolchains_workspace_test",
-    bazel_versions = [
-        version
-        for version in bazel_binaries.versions.all
-        if not version.startswith("6.")
-    ],
     bzlmod = False,
+    env = {
+        "RULES_PYTHON_BZLMOD_DEBUG": "1",
+    },
     workspace_path = "local_toolchains",
 )