FEAT: Added new height and width query parameters

[seekayel]

Purpose

When using github-readme-stats generated assets in situations that need specific aspect ratios (eg social preview for websites) it is helpful to lock the generated image to a specific size.

This PR adds new query parameters of height and width which lock the produced svg size to all stats card types.

Example: To match social card 1200x630 aspect ratio: https://github-readme-stats.vercel.app/api?username=anuraghazra&width=600&height=315

[vercel[bot]]

@seekayel is attempting to deploy a commit to the github readme stats Team on Vercel.

A member of the Team first needs to authorize it.

[seekayel]

I'm willing to keep the PR updated with base and make any requested changes if it is valuable to the project. However not sure I want to do that if its not of interest.

Let me know if this has a shot of getting merged.