chore(site): fix material ui warning (#4161)

* chore(deps): upgrade @material-ui/core to 4.12.4

This is the latest version which includes a fix for the warning we were
seeing while running our tests about `css` function being deprecated.

* refactor: use alpha() instead of fade

`fade()` was deprecated in favor of `alpha()` in a previous version of
`@material-ui/core/styles`.

* refactor: rows -> minRows

This was deprecated in a previous version of `@material-ui/core`.

* refactor: overlap circle -> circular

overlap="circle" was deprecated in favor of overlap="circular".

* refactor: createMuiTheme -> createTheme

This was deprecated and changed to `createTheme`.

* fixup!: chore(deps): upgrade @material-ui/core to 4.12.4

* fixup!: refactor: createMuiTheme -> createTheme

* fix: add SvgIconProps on icons

I couldn't find any release notes or breaking changes related to this
but it seems `props` can no longer be inferred on `SvgIcon`s so I had to
manually add the type.

* Revert "refactor: rows -> minRows"

This reverts commit 94dae6fea8.

* chore(deps): downgrade @material-ui/core to 4.12.0

* fixup!: fix: add SvgIconProps on icons

* fix: pass {} to useStyles

Looks like we may need to pass an empty object if some components in a
file use `props` in styles and some don't.

* fix: update types in Pill.tsx

We need to use generics so that `makeStyles` correctly infers the types
for the `Pill.tsx` styles.

I also updated the types to use `PillProps` directly to make sure they
stay in sync.

site/package.json

@@ -30,7 +30,7 @@
     "@emoji-mart/react": "^1.0.1",
     "@fontsource/ibm-plex-mono": "4.5.10",
     "@fontsource/inter": "4.5.11",
-    "@material-ui/core": "4.9.4",
+    "@material-ui/core": "4.12.1",
     "@material-ui/icons": "4.5.1",
     "@material-ui/lab": "4.0.0-alpha.42",
     "@testing-library/react-hooks": "8.0.1",