Describe the bug

The type has changed and now I am getting linting errors on a working code.
I get Element implicitly has an 'any' type because index expression is not of type 'number'.ts(7015) error when I try to access the headers by their name on a AxiosRequestHeaders object.

For example accessing a common header in transfomRequest where the content of headers is:

If I try to access the common Accept header key, then I will get the above error.

I think the issue is at:

The type should be:

export type AxiosRequestHeaders = Record<string, Record<string, string>>; 

Possibly the AxiosResponseHeaders has the same issue.

To Reproduce

import axios from 'axios'

axios({
    method: 'post',
    url: '/user/12345',
    data: {
        firstName: 'Fred',
        lastName: 'Flintstone',
    },
    transformRequest: (_, headers) => {
        if(headers)
            delete headers.common['Accept'] //Error occurs here
    },
})
    .then(function (response) {
        console.log(response)
    })
    .catch(function (error) {
        console.log(error)
    })

Expected behavior

Expected to not raise an error there

Environment

• Axios 0.23.0
• TypeScript 4.4.4

Additional context/Screenshots