Use [pandas] rather than [express]

Author: ndrezn

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

@@ -15,7 +15,7 @@
 
 Or install Plotly Express and its dependencies directly with:
 
-$ pip install "plotly[express]"
+$ pip install "plotly[pandas]"
 
 You can also use Plotly Graph Objects to create a large number of charts without installing
 pandas. See examples here: https://plotly.com/python/graph-objects/

Diff for: packages/python/plotly/requires-express.txt renamed to packages/python/plotly/requires-pandas.txt

@@ -609,7 +609,7 @@ def read_req_file(req_type):
     ],
     install_requires=read_req_file("install"),
     extras_require={
-        "express": read_req_file("express"),
+        "pandas": read_req_file("pandas"),
         "dev": read_req_file("dev"),
     },
     zip_safe=False,