Add a missing scheme when getting the Element .well-known file.

[pixlwave]

As reported by @bmarty (thanks!).

[github-actions[bot]]

	Warnings
:warning:	Some of the commits are missing ticket numbers. Please consider squashing all commits that don't have a tracking number.

Generated by :no_entry_sign: Danger Swift against 2df1485c340a7cf6b750af58b73f7d2bab6f3f30

[sonarcloud[bot]]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarCloud

[codecov[bot]]

Codecov Report

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

Project coverage is 77.82%. Comparing base (dac363c) to head (2df1485).

Additional details and impacted files

```diff @@ Coverage Diff @@ ## develop #2995 +/- ## ======================================== Coverage 77.82% 77.82% ======================================== Files 694 694 Lines 53834 53834 ======================================== Hits 41897 41897 Misses 11937 11937 ``` | [Flag](https://app.codecov.io/gh/element-hq/element-x-ios/pull/2995/flags?src=pr&el=flags&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=element-hq) | Coverage Δ | | |---|---|---| | [unittests](https://app.codecov.io/gh/element-hq/element-x-ios/pull/2995/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=element-hq) | `68.47% <ø> (-0.04%)` | :arrow_down: | 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=element-hq#carryforward-flags-in-the-pull-request-comment) to find out more.

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