fix(client): handle the final slash sensitivity on core routers

[frgfm]

This PR introduces the following modifications:

• reflects the final slash in the endpoint of base router (cf. https://github.com/pyronear/pyro-api/blob/main/src/app/api/endpoints/sites.py#L22) by modifying the client routes
• make sure the API is redirecting to the trailing slash endpoint in the backend to avoid problems later
• add a test case in the integration test script
• speeds up the dependencies installation in the Docker images

Any feedback is welcome! cc @MateoLostanlen

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 94.39%. Comparing base (86f426c) to head (b5737ea).

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #317 +/- ## ========================================== - Coverage 94.59% 94.39% -0.21% ========================================== Files 63 66 +3 Lines 1591 1676 +85 ========================================== + Hits 1505 1582 +77 - Misses 86 94 +8 ``` | [Flag](https://app.codecov.io/gh/pyronear/pyro-api/pull/317/flags?src=pr&el=flags&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=pyronear) | Coverage Δ | | |---|---|---| | [client](https://app.codecov.io/gh/pyronear/pyro-api/pull/317/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=pyronear) | `90.58% <ø> (?)` | | | [unittests](https://app.codecov.io/gh/pyronear/pyro-api/pull/317/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=pyronear) | `94.59% <100.00%> (ø)` | | Flags with carried forward coverage won't be shown. [Click here](https://docs.codecov.io/docs/carryforward-flags?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=pyronear#carryforward-flags-in-the-pull-request-comment) to find out more.

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[MateoLostanlen]

Thanks @frgfm for fixing this bug and for adding the test, let me know when you've fixed it :smiley:

[frgfm]

Alright, all tests passed, everything is backward compatible! I'll merge this to clean up other things in the mean time