Fix a bug regarding timedelta64[ms] representation

Author: kaibir

Diff for: .circleci/config.yml

@@ -150,6 +150,15 @@ jobs:
       - test_optional:
           py: "39"
 
+  # Pandas
+
+  python_39_pandas_2_optional:
+    docker:
+      - image: circleci/python:3.9-buster-node-browsers
+    steps:
+      - test_optional:
+          py: "39_pandas_2"
+
   # Orca
   python_38_orca:
     docker:
@@ -470,6 +479,7 @@ workflows:
       - python_37_optional
       - python_38_optional
       - python_39_optional
+      - python_39_pandas_2_optional
       - python_38_orca
       - python_37_percy
       - build-doc

Diff for: packages/python/plotly/plotly/express/_core.py

@@ -1682,7 +1682,9 @@ def process_dataframe_timeline(args):
         )
 
     # note that we are not adding any columns to the data frame here, so no risk of overwrite
-    args["data_frame"][args["x_end"]] = (x_end - x_start).astype("timedelta64[ms]")
+    args["data_frame"][args["x_end"]] = (x_end - x_start).astype(
+        "timedelta64[ns]"
+    ) / np.timedelta64(1, "ms")
     args["x"] = args["x_end"]
     del args["x_end"]
     args["base"] = args["x_start"]

Diff for: packages/python/plotly/test_requirements/requirements_39_pandas_2_optional.txt

@@ -0,0 +1,21 @@
+requests==2.25.1
+tenacity==6.2.0
+pandas==2.0.0rc1
+numpy==1.20.3
+xarray==0.17.0
+statsmodels
+Pillow==8.2.0
+pytest==6.2.3
+pytz==2021.1
+ipython[all]==7.22.0
+ipywidgets==8.0.2
+ipykernel==5.5.3
+jupyter==1.0.0
+scipy==1.6.2
+Shapely==1.7.1
+geopandas==0.9.0
+pyshp==2.1.3
+matplotlib==2.2.3
+scikit-image==0.18.1
+psutil==5.7.0
+kaleido