Prepare 6.1.0 release

[aduth]

Changelog:

6.1.0

Improvements

• USWDS is upgraded to the latest version, from v2.11.2 to v2.12.1.
• Whitespace in checkbox and radio label markup will no longer cause the label text to be misplaced.
• Margins surrounding an external link icon have been increased slightly.
• Padding and label font size for tile checkboxes and radio buttons have increased slightly.

[mdiarra3]

Visual regression failed weirdly enough.

[aduth]

Visual regression failed weirdly enough.

It's expected for these kinds of version bumps, unfortunately. It's because we show the version number on the homepage, which is picked up by the visual regression comparison.