fix: adds test cases using the official Receita Federal example (12.ABC.345/01DE-35) to prevent future regressions

Author: lindsay-qive

src/format-cnpj/format-cnpj.test.ts

@@ -116,4 +116,16 @@ describe("formatCnpj", () => {
 			"46.ABC.843/4850-00",
 		);
 	});
+
+	it("should allow all alphabet letters for version 2 (including E, O, T, U)", () => {
+        expect(formatCnpj("12ABC34501DE35", { version: 2 })).toBe(
+            "12.ABC.345/01DE-35"
+        );
+        expect(formatCnpj("12.ABC.345/01DE-35", { version: 2 })).toBe(
+            "12.ABC.345/01DE-35"
+        );
+        expect(formatCnpj("12OUT345000199", { version: 2 })).toBe(
+            "12.OUT.345/0001-99"
+        );
+    });
 });