Deprecate `uniforms-material` theme

[zendranm]

Deprecating the Material theme, as mentioned in this issue (https://github.com/vazco/uniforms/issues/1315).

• Removed the whole package from the uniforms repository
• Removed package from the labeler
• Removed Material from the Readme file
• Removed the uniforms-material package from the package.json files
• Removed theme from tsconfig references
• Removed skipTestIf from test suites

[codecov[bot]]

Codecov Report

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

Project coverage is 95.05%. Comparing base (c047291) to head (946faf6).

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #1338 +/- ## ========================================== + Coverage 94.35% 95.05% +0.69% ========================================== Files 200 175 -25 Lines 3314 2892 -422 Branches 895 763 -132 ========================================== - Hits 3127 2749 -378 + Misses 70 59 -11 + Partials 117 84 -33 ```

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[kestarumper]

I wonder if we should add somewhere in the docs an admonition that this theme has been deprecated. But I don't know where since there are no dedicated pages for a theme.

[wadamek65]

@kestarumper Maybe you could add it in the installation section when picking the material theme? It's probably very niche but better than nothing I suppose.

[kestarumper]

@wadamek65, but we're getting rid of the Material tab button fully (this is because we're deleting all dependencies such as styles, etc).

[wadamek65]

@kestarumper Then another option would be modifying the README in the package itself, so at least it will be shown on the npm page of the package.

[kestarumper]

@wadamek65 well, we're deleting the README too 😅. We planned to use the NPM deprecation message.

[wadamek65]

@kestarumper Then I'm out of ideas 😖

[Monteth]

@kestarumper We can release the last version with deprecation info and then remove the package, so in the history, there will be a readme with a message.

[ErnestTeluk]

conflict to fix