fix(core): use own font interface, do not rely on react

Instead of using CSSProperties that require to have React as a dependency even for a core package,
write own Font interface.

fixes #811

packages/core/src/helpers/font/font.ts

@@ -1,5 +1,4 @@
 import { toCSS } from '@onfido/castor';
-import { CSSProperties } from 'react';
 
 /**
  * Returns an object that represents a `Font`.
@@ -39,10 +38,13 @@ export function font(name: FontName): Font {
   return { ...styles, toString: () => toCSS(styles) } as Font;
 }
 
-export type Font = Pick<
-  CSSProperties,
-  `font${'Family' | 'Size' | 'Weight'}` | 'lineHeight' | 'textTransform'
->;
+export interface Font {
+  fontFamily: string;
+  fontSize: string;
+  fontWeight: number;
+  lineHeight: string;
+  textTransform: string;
+}
 
 export type FontName =
   | `${FontSize}-bold`