fix(src): replace ==/!= with ===/!== (#140)

Sources such as [D. Crockford][^1] and [MDN][^2] both advise that only
triple equals operator should be used when programming in JavaScript
and double equals operator be ignored altogether.

[^1]:
    https://bytearcher.com/articles/douglas-crockford-javascript-good-parts-book-review/

[^2]:
    https://developer.mozilla.org/en-US/docs/Web/JavaScript/Equality_comparisons_and_sameness#Loose_equality_using

Co-authored-by: deepsource-autofix[bot] <62050782+deepsource-autofix[bot]@users.noreply.github.com>

src/index.ts

@@ -130,7 +130,7 @@ export function objectsEqualShallow(
   o1: Record<string, number | RegExp> | null | undefined,
   o2: Record<string, number | RegExp> | null | undefined
 ): boolean {
-  if (o1 == null || o2 == null) {
+  if (o1 === null || o2 === null) {
     // Null is only equal to null, and undefined to undefined.
     return o1 === o2;
   }