🚚(backend) rename Impress to Meet

I have updated all references of "Impress" to "Meet".
Migrations were manually updated and not regenerated. Never-mind,
they all will be squashed before the first release.

I have also searched for reference to "Magnify", and replaced them
by "Meet".

While updating the backend sources, I have also fixed other parts of
the project, namely:
- Compose file
- Github documentation and CI
- Makefile commands

.github/ISSUE_TEMPLATE/Bug_report.md

@@ -18,7 +18,7 @@ A clear and concise description of what you expected to happen (or code).
 3. And then the bug happens!
 
 **Environment**
-- Impress version:
+- Meet version:
 - Platform:
 
 **Possible Solution**

.github/ISSUE_TEMPLATE/Support_question.md

@@ -9,9 +9,9 @@ We primarily use GitHub as an issue tracker. If however you're encountering an i
 
 ---
 
-Please make sure you have read our [main Readme](https://github.com/numerique-gouv/impress).
+Please make sure you have read our [main Readme](https://github.com/numerique-gouv/meet).
 
-Also make sure it was not already answered in [an open or close issue](https://github.com/numerique-gouv/impress/issues).
+Also make sure it was not already answered in [an open or close issue](https://github.com/numerique-gouv/meet/issues).
 
 If your question was not covered, and you feel like it should be, fire away! We'd love to improve our docs! 👌