Move from httpretty to mocket as http mocking library (#4583)

* opentelemetry-instrumentation-urllib: move from httpretty to mocker

* opentelemetry-instrumentation-urllib3: move from httpretty to mocket

* opentelemetry-instrumentation-requests: move from httpretty to mocket

* dev-requirements: drop httpretty as it's not used anymore

* Add changelog

* generate worflows