message: Update Heading component TypeScript type definition
diff: @@ -70,7 +70,9 @@ declare module '@primer/components' {
  extends BaseProps,
  CommonProps,
  TypographyProps,
  - Omit<React.HTMLAttributes<HTMLHeadingElement>, 'color'> {}
  + Omit<React.HTMLAttributes<HTMLHeadingElement>, 'color'> {
  + as?: 'h1' | 'h2' | 'h3' | 'h4' | 'h5' | 'h6'
  + }
  export const Heading: React.FunctionComponent<HeadingProps>
  