docs: remove disableTransitionOnChange from ThemeProvider example

[mrbonk97]

PR Description:

• The example previously included disableTransitionOnChange, which disables all CSS transitions during theme changes.
• As a result, the ModeToggle button's icon animations (e.g., rotation) were not visible.
  This option has been removed so the example behaves as expected.

Changes:

• Removed disableTransitionOnChange from the ThemeProvider example

[vercel]

@mrbonk97 is attempting to deploy a commit to the shadcn-pro Team on Vercel.

A member of the Team first needs to authorize it.