update constraints files

Author: Linchin

testing/constraints-3.8.txt

@@ -14,7 +14,7 @@ google-auth-oauthlib==0.7.0
 google-cloud-bigquery==3.4.2
 google-cloud-bigquery-storage==2.16.2
 numpy==1.18.1
-pandas==1.1.4
+pandas==1.3.0
 pyarrow==4.0.0
 pydata-google-auth==1.5.0
 Shapely==1.8.4

testing/constraints-3.9.txt

@@ -1,2 +1,2 @@
 numpy==1.19.4
-pandas==1.1.4
+pandas==1.3.0