Upgrade typescript-eslint to 4.x (#2056)

This is updated to officially support eslint 7.x (avoid a peer
dependency install error), and also officially match the current
TypeScript version (typescrlint-eslint 2.x doesn't officically support
TypeScript 4.x).

Without this fix, I just get an error upon 'npm install'.

I disabled some of the new rules that caused a lot of errors, but they
can probably be fixed and enabled in subsequent commits (there are a lot
of other lint warnings that can be tackled as well, though).

Author: stianjensen

.eslintrc.js

@@ -29,6 +29,8 @@ module.exports = {
     'react/jsx-uses-vars': 2,
     '@typescript-eslint/no-use-before-define': 0,
     '@typescript-eslint/no-var-requires': 0,
-    '@typescript-eslint/explicit-function-return-type': 0
+    '@typescript-eslint/explicit-function-return-type': 0,
+    '@typescript-eslint/ban-types': 0,
+    '@typescript-eslint/ban-ts-comment': 1
   }
 };

example/src/mocks/theme.ts

@@ -1,4 +1,4 @@
-import {Platform} from "react-native";
+import {Platform} from 'react-native';
 
 export const themeColor = '#00AAAF';
 export const lightThemeColor = '#f2f7f7';
@@ -16,18 +16,18 @@ export function getTheme() {
     monthTextColor: 'black',
     textMonthFontSize: 16,
     textMonthFontFamily: 'HelveticaNeue',
-    textMonthFontWeight: 'bold' as 'bold',
+    textMonthFontWeight: 'bold' as const,
     // day names
     textSectionTitleColor: 'black',
     textDayHeaderFontSize: 12,
     textDayHeaderFontFamily: 'HelveticaNeue',
-    textDayHeaderFontWeight: 'normal' as 'normal',
+    textDayHeaderFontWeight: 'normal' as const,
     // dates
     dayTextColor: themeColor,
     todayTextColor: '#af0078',
     textDayFontSize: 18,
     textDayFontFamily: 'HelveticaNeue',
-    textDayFontWeight: '500' as '500',
+    textDayFontWeight: '500' as const,
     textDayStyle: {marginTop: Platform.OS === 'android' ? 2 : 4},
     // selected date
     selectedDayBackgroundColor: themeColor,

package.json

@@ -52,8 +52,8 @@
     "@types/react": "^17.0.44",
     "@types/react-native": "^0.64.19",
     "@types/xdate": "^0.8.32",
-    "@typescript-eslint/eslint-plugin": "^2.13.0",
-    "@typescript-eslint/parser": "^2.13.0",
+    "@typescript-eslint/eslint-plugin": "^4.0.0",
+    "@typescript-eslint/parser": "^4.0.0",
     "@welldone-software/why-did-you-render": "^6.0.3",
     "babel-eslint": "^10.1.0",
     "babel-jest": "^26.6.3",

src/utils/__tests__/Playground.perf.js

@@ -1,6 +1,6 @@
 import React from 'react';
 import {measurePerformance} from 'reassure';
-import {Calendar, CalendarList} from '../../index';
+import {Calendar, CalendarList, ExpandableCalendar} from '../../index';
 
 const INITIAL_DATE = '2022-07-07';