[TextField] red error text fails a11y contrast ratio requirement of 4.5:1

[slayybelle]

Even on a white background, the error text for [TextField] is flagged at < 4.5:1 ratio, unacceptable for accessibility

• The issue is present in the latest release.
• I have searched the issues of this repository and believe that this is not a duplicate.

Current Behavior 😯

The default red error text is too light against the best-case white background

Expected Behavior 🤔

It should be at least 4.5:1 on a white background; Default behavior on hover often darkens the background, requiring an even darker red to pass

Steps to Reproduce 🕹

Steps:

1. https://next.material-ui.com/components/text-fields/
2. Go to Validation section where there's demo of red error text
3. I'll attach a pic where I open dev tools and use Lighthouse element inspector to inspect the text and it flags the contrast violation

Context 🔦

a11y testing; conformance required by customers

Your Environment 🌎

Your demo page (see url above, step 1); also happens on latest 4.x

[slayybelle]

Here's a work-around I will do: Add to createMuiTheme:

MuiFormLabel: {
            root: {
                "&$error": {
                    color: COLOR_DM_BG_LIGHTEST_RED,
                }
            }
        },
        MuiFormHelperText: {
            root: {
                "&$error": {
                    color: COLOR_DM_BG_LIGHTEST_RED,
                }
            }
        },

where:
export const COLOR_DM_BG_LIGHTEST_RED = "#DE3421";