FastAPI Example updated demo url (#1238)

### Description

Updated demo url

### Demo URL

https://vercel-plus-fastapi.vercel.app/

### Type of Change

- [ ] New Example
- [x] Example updates (Bug fixes, new features, etc.)
- [ ] Other (changes to the codebase, but not to examples)

### New Example Checklist

- [ ] 🛫 `npm run new-example` was used to create the example
- [ ] 📚 The template wasn't used but I carefuly read the [Adding a new
example](https://github.com/vercel/examples#adding-a-new-example) steps
and implemented them in the example
- [x] 📱 Is it responsive? Are mobile and tablets considered?

Author: ricardo-agz

python/fastapi/README.md

@@ -1,12 +1,12 @@
-[![Deploy with Vercel](https://vercel.com/button)](https://vercel.com/new/clone?repository-url=https%3A%2F%2Fgithub.com%2Fvercel%2Fexamples%2Ftree%2Fmain%2Fpython%2Ffastapi&demo-title=FastAPI&demo-description=Use%20FastAPI%20on%20Vercel%20with%20Serverless%20Functions%20using%20the%20Python%20Runtime.&demo-url=https%3A%2F%2Fvercel-fastapi-gamma-smoky.vercel.app%2F&demo-image=https://assets.vercel.com/image/upload/v1669994600/random/python.png)
+[![Deploy with Vercel](https://vercel.com/button)](https://vercel.com/new/clone?repository-url=https%3A%2F%2Fgithub.com%2Fvercel%2Fexamples%2Ftree%2Fmain%2Fpython%2Ffastapi&demo-title=FastAPI&demo-description=Use%20FastAPI%20on%20Vercel%20with%20Serverless%20Functions%20using%20the%20Python%20Runtime.&demo-url=https%3A%2F%2Fvercel-plus-fastapi.vercel.app%2F&demo-image=https://assets.vercel.com/image/upload/v1669994600/random/python.png)
 
 # FastAPI + Vercel
 
 This example shows how to use FastAPI on Vercel with Serverless Functions using the [Python Runtime](https://vercel.com/docs/concepts/functions/serverless-functions/runtimes/python).
 
 ## Demo
 
-https://vercel-fastapi-gamma-smoky.vercel.app/
+https://vercel-plus-fastapi.vercel.app/
 
 ## How it Works
 
@@ -25,4 +25,4 @@ Your FastAPI application is now available at `http://localhost:3000`.
 
 Deploy the example using [Vercel](https://vercel.com?utm_source=github&utm_medium=readme&utm_campaign=vercel-examples):
 
-[![Deploy with Vercel](https://vercel.com/button)](https://vercel.com/new/clone?repository-url=https%3A%2F%2Fgithub.com%2Fvercel%2Fexamples%2Ftree%2Fmain%2Fpython%2Ffastapi&demo-title=FastAPI&demo-description=Use%20FastAPI%20on%20Vercel%20with%20Serverless%20Functions%20using%20the%20Python%20Runtime.&demo-url=https%3A%2F%2Fvercel-fastapi-gamma-smoky.vercel.app%2F&demo-image=https://assets.vercel.com/image/upload/v1669994600/random/python.png)
+[![Deploy with Vercel](https://vercel.com/button)](https://vercel.com/new/clone?repository-url=https%3A%2F%2Fgithub.com%2Fvercel%2Fexamples%2Ftree%2Fmain%2Fpython%2Ffastapi&demo-title=FastAPI&demo-description=Use%20FastAPI%20on%20Vercel%20with%20Serverless%20Functions%20using%20the%20Python%20Runtime.&demo-url=https%3A%2F%2Fvercel-plus-fastapi.vercel.app%2F&demo-image=https://assets.vercel.com/image/upload/v1669994600/random/python.png)