chore(main): release 2.30.0 (#914)

* chore(main): release 2.30.0

* 🦉 Updates from OwlBot post-processor

See https://github.com/googleapis/repo-automation-bots/blob/main/packages/owl-bot/README.md

---------

Co-authored-by: release-please[bot] <55107282+release-please[bot]@users.noreply.github.com>
Co-authored-by: Owl Bot <gcf-owl-bot[bot]@users.noreply.github.com>

Author: release-please[bot]

bigquery_storage/generated_samples/snippet_metadata_google.cloud.bigquery.storage.v1.json

@@ -8,7 +8,7 @@
     ],
     "language": "PYTHON",
     "name": "google-cloud-bigquery-storage",
-    "version": "0.1.0"
+    "version": "2.30.0"
   },
   "snippets": [
     {

bigquery_storage/generated_samples/snippet_metadata_google.cloud.bigquery.storage.v1beta2.json

@@ -8,7 +8,7 @@
     ],
     "language": "PYTHON",
     "name": "google-cloud-bigquery-storage",
-    "version": "0.1.0"
+    "version": "2.30.0"
   },
   "snippets": [
     {

bigquery_storage/pyarrow/append_rows_with_arrow.py

@@ -15,15 +15,15 @@
 # limitations under the License.
 import datetime
 import decimal
+
+from google.cloud.bigquery import enums
 import pandas as pd
 import pyarrow as pa
 
 from google.cloud import bigquery
-from google.cloud.bigquery import enums
 from google.cloud.bigquery_storage_v1 import types as gapic_types
 from google.cloud.bigquery_storage_v1.writer import AppendRowsStream
 
-
 TABLE_LENGTH = 100_000
 
 BQ_SCHEMA = [