chore: bump minimum pyarrow version

Author: judahrand

setup.py

@@ -54,11 +54,11 @@
         # grpc.Channel.close() method isn't added until 1.32.0.
         # https://github.com/grpc/grpc/pull/15254
         "grpcio >= 1.38.1, < 2.0dev",
-        "pyarrow >= 3.0.0, < 6.0dev",
+        "pyarrow >= 4.0.0, < 6.0dev",
     ],
     "geopandas": ["geopandas>=0.9.0, <1.0dev", "Shapely>=1.6.0, <2.0dev"],
-    "pandas": ["pandas>=0.23.0", "pyarrow >= 3.0.0, < 6.0dev"],
-    "bignumeric_type": ["pyarrow >= 3.0.0, < 6.0dev"],
+    "pandas": ["pandas>=0.23.0", "pyarrow >= 4.0.0, < 6.0dev"],
+    "bignumeric_type": ["pyarrow >= 4.0.0, < 6.0dev"],
     "tqdm": ["tqdm >= 4.7.4, <5.0.0dev"],
     "opentelemetry": [
         "opentelemetry-api >= 0.11b0",

testing/constraints-3.6.txt

@@ -17,7 +17,7 @@ opentelemetry-sdk==0.11b0
 pandas==0.24.2
 proto-plus==1.10.0
 protobuf==3.12.0
-pyarrow==3.0.0
+pyarrow==4.0.0
 requests==2.18.0
 Shapely==1.6.0
 six==1.13.0

tests/system/test_arrow.py

@@ -23,8 +23,8 @@
 
 
 pyarrow = pytest.importorskip(
-    "pyarrow", minversion="3.0.0"
-)  # Needs decimal256 for BIGNUMERIC columns.
+    "pyarrow", minversion="4.0.0"
+)  # Needs `use_compliant_nested_type` for `load_table_from_dataframe`.
 
 
 @pytest.mark.parametrize(