GitHub file size badge doesn't work for some files

### Are you experiencing an issue with...

shields.io

### 🐞 Description

This badge works for most files
https://img.shields.io/github/size/badges/shields/server.js
but there are some that cause a problem
https://img.shields.io/github/size/badges/shields/package.json
The reason this fails is because this causes us to look for a file called "package" and use json output format, rather than look for a file called "package.json"

### 🔗 Link to the badge

https://img.shields.io/github/size/badges/shields/package.json

### 💡 Possible Solution

We might need to switch `path` from a path param to a query param to solve this.

Start with the GitHub size badge endpoint shown in the issue and trace how its path is parsed into a filename and output format. Reproduce the failing package.json URL and compare it with server.js; done means both badges resolve the intended complete filename and return the expected badge output.

Written by the indexing model from the issue text.