[Stepper] Expanded prop missing from typescript

[countableSet]

• The issue is present in the latest release.
• I have searched the issues of this repository and believe that this is not a duplicate.

Current Behavior 😯

Looks like a new prop was added to the stepper component for expanding steps, however, looks like it's missing from the typescript definition.

caused by;
#19200
missing from ts definition;
https://github.com/mui-org/material-ui/blob/49e1adf94bfe383ce819dce121f910a5c47bafbf/packages/material-ui/src/Step/Step.d.ts

Expected Behavior 🤔

Should be able to override the expanded prop in typescript.

Steps to Reproduce 🕹

https://codesandbox.io/s/frosty-darkness-tgcqu

Steps:

1. Create a stepper component
2. Add a step
3. Try to add prop expanded
4. Doesn't find it

Context 🔦

Your Environment 🌎

Tech	Version
Material-UI	v4.9.4
React	16.9.11
Browser	Firefox 72.0.2
TypeScript	3.7.2

[oliviertassinari]

@countableSet Thanks for the report. What do you think of this patch?

git fetch https://github.com/FottyM/material-ui "patch-2"
diff --git a/packages/material-ui/src/Step/Step.d.ts b/packages/material-ui/src/Step/Step.d.ts
index 84ad12089..d60607b73 100644
--- a/packages/material-ui/src/Step/Step.d.ts
+++ b/packages/material-ui/src/Step/Step.d.ts
@@ -10,6 +10,7 @@ export interface StepProps
   completed?: boolean;
   connector?: React.ReactElement;
   disabled?: boolean;
+  expanded?: boolean;
   index?: number;
   last?: boolean;
   orientation?: Orientation;

Do you want to submit a pull request :)?