[webclient] bug fix to double URL encoding

[zapek]

DefaultWebClient() already encodes URL query parameters.

Without this PR, I have a request with title=foo bar which gets converted to title=foo%25%20bar.
With this PR, the request becomes title=foo%20bar

This fixes#8171

[wing328]

Tested locally and the result is good:

HTTP: GET /v2/pet/12345?query_test=foo%20bar HTTP/1.1

I'll update the sample after merging this PR into master.

I'll also try to come up with a PR later to update the dependencies as there are newer versions available.

[wing328]

Filed #8972 to update webclient dependencies. Please kindly review when you've time.

[wing328]

@zapek thanks for the PR, which has been included in the v5.1.0 release: https://twitter.com/oas_generator/status/1373636654024380423

[fbecaria]

@wing328 A question regarding this issue, considering the example you mention before (which shows the change fix the issue), I see that fails if the query param include an "&". My solution so far is to remove encoding at all and encode query params manually.