Add a start date option to ignore old issues and PRs (#269)

* docs(readme): add a small precision about the operations-per-run

closes #230

* chore(lint): ignore the lib folder for prettier

* chore(date): add a function to check if a date is valid

* chore(date): add a function to get a humanized date

* chore(date): add a function to check if the date is more recent than

* feat(date): add a start date to ignore old issues and PRs

closes #174

* docs(readme): change the date to match the description

* chore(date): add a better type for the date

* docs(date): add missing JSDoc about the return type

* chore(rebase): fix issues due to rebase

* docs(readme): fix table formatting issues

src/functions/dates/is-valid-date.spec.ts

@@ -0,0 +1,61 @@
+import {isValidDate} from './is-valid-date';
+
+describe('isValidDate()', (): void => {
+  let date: Date;
+
+  describe('when the given date is an invalid date', (): void => {
+    beforeEach((): void => {
+      date = new Date('16-04-1994');
+    });
+
+    it('should return false', (): void => {
+      expect.assertions(1);
+
+      const result = isValidDate(date);
+
+      expect(result).toStrictEqual(false);
+    });
+  });
+
+  describe('when the given date is a new date', (): void => {
+    beforeEach((): void => {
+      date = new Date();
+    });
+
+    it('should return true', (): void => {
+      expect.assertions(1);
+
+      const result = isValidDate(date);
+
+      expect(result).toStrictEqual(true);
+    });
+  });
+
+  describe('when the given date is an ISO and valid date', (): void => {
+    beforeEach((): void => {
+      date = new Date('2011-04-22T13:33:48Z');
+    });
+
+    it('should return true', (): void => {
+      expect.assertions(1);
+
+      const result = isValidDate(date);
+
+      expect(result).toStrictEqual(true);
+    });
+  });
+
+  describe('when the given date is an ISO with ms and valid date', (): void => {
+    beforeEach((): void => {
+      date = new Date('2011-10-05T14:48:00.000Z');
+    });
+
+    it('should return true', (): void => {
+      expect.assertions(1);
+
+      const result = isValidDate(date);
+
+      expect(result).toStrictEqual(true);
+    });
+  });
+});