Prevent double request interception on POST

[JeppeKnockaert]

When submitting a post request through Browsershot you get the following error:

Error: Request is already handled!
    at assert (browsershot/node_modules/puppeteer/lib/cjs/puppeteer/common/assert.js:28:15)
    at HTTPRequest.continue (browsershot/node_modules/puppeteer/lib/cjs/puppeteer/common/HTTPRequest.js:349:32)
    at browsershot/bin/browser.js:198:40
    at browsershot/node_modules/puppeteer/lib/cjs/puppeteer/common/Page.js:275:32
    at process.processTicksAndRejections (node:internal/process/task_queues:95:5)
    at async HTTPRequest.finalizeInterceptions (browsershot/node_modules/puppeteer/lib/cjs/puppeteer/common/HTTPRequest.js:188:9)

This is caused by intercepting the request twice in the browser.js script.

I've added a test that performs a real post which fails on the existing code and works after the change.

[freekmurze]

Thanks!