samples: remove references to Python 3.9 (#18622)

Author: parthea

packages/google-cloud-bigquery-storage/samples/to_dataframe/requirements.txt

@@ -1,19 +1,10 @@
 google-auth==2.52.0
 google-cloud-bigquery-storage==2.38.0
-google-cloud-bigquery==3.30.0; python_version <= '3.8'
-google-cloud-bigquery==3.41.0; python_version >= '3.9'
-pyarrow==12.0.1; python_version == '3.7'
-pyarrow==17.0.0; python_version == '3.8'
-pyarrow==24.0.0; python_version >= '3.9'
-ipython==7.31.1; python_version == '3.7'
-ipython==8.10.0; python_version == '3.8'
-ipython==8.18.1; python_version == '3.9'
-ipython==8.33.0; python_version == '3.10'
+google-cloud-bigquery==3.41.0
+pyarrow==24.0.0
+ipython===8.33.0; python_version == '3.10'
 ipython==9.13.0; python_version >= '3.11'
 ipywidgets==8.1.8
-pandas==1.3.5; python_version == '3.7'
-pandas==2.0.3; python_version == '3.8'
-pandas==2.3.3; python_version >= '3.9'
+pandas==2.3.3
 tqdm==4.67.3
-db-dtypes==1.4.2; python_version <= '3.8'
-db-dtypes==1.6.0; python_version >= '3.9'
+db-dtypes==1.6.0

packages/google-cloud-bigtable/samples/legacy_client/beam/requirements.txt

@@ -1,5 +1,3 @@
-apache-beam==2.60.0; python_version == '3.8'
-apache-beam==2.69.0; python_version == '3.9'
-apache-beam==2.71.0; python_version >= '3.10'
+apache-beam==2.71.0
 google-cloud-bigtable==2.35.0
 google-cloud-core==2.5.0