Fix Verification Digits not being calculated with clean string (#16)

Author: LeoColman

src/main/kotlin/br/com/colman/simplecpfvalidator/CpfValidator.kt

@@ -39,7 +39,7 @@ import kotlin.math.abs
 fun String.isCpf(charactersToIgnore: List<Char> = listOf('.', '-')): Boolean {
     val cleanCpf = this.filterNot { it in charactersToIgnore }
     if (cleanCpf.containsInvalidCPFChars() || cleanCpf.isInvalidCpfSize() || cleanCpf.isBlacklistedCpf()) return false
-    return this.hasValidVerificationDigits()
+    return cleanCpf.hasValidVerificationDigits()
 }
 
 /**

src/test/kotlin/br/com/colman/simplecpfvalidator/CpfValidatorTest.kt

@@ -43,7 +43,7 @@ class CpfValidatorTest : FunSpec({
     }
 
     test("Should sanitize the String given replaceable characters and still return true on valid cpfs") {
-        ValidCpfGenerator.map { "$it..--." }.forAll { cpf -> cpf.isCpf(listOf('.', '-')) }
+        ValidCpfGenerator.map { "..--.$it..--." }.forAll { cpf -> cpf.isCpf(listOf('.', '-')) }
     }
 
     test("Shouldn't sanitize unspecified characters") {