Fix regex detection (#596)

`\Foo\A` is detected as a regex and whilst this is true (`\` used as a delimiter here with the flag `A`), it makes a lot of things complicated for an edge case which IMO has no reasons to be: if you wish such a regex simply use another delimiter.

Author: theofidry

src/RegexChecker.php

@@ -43,6 +43,11 @@ public function isRegexLike(string $value): bool
 
         $firstCharacter = $value[0];
 
+        if ('\\' === $firstCharacter) {
+            // This is not ideal as not true.
+            return false;
+        }
+
         $parts = explode($firstCharacter, $value);
 
         if (false === $parts || count($parts) !== 3) {

tests/RegexCheckerTest.php

@@ -64,11 +64,16 @@ public static function regexLikeProvider(): iterable
             true,
         ];
 
-        yield 'fake regex' => [
+        yield 'fake regex (0)' => [
             '/Foo/Bar/',
             false,
         ];
 
+        yield 'fake regex (1)' => [
+            '\Foo\A',
+            false,
+        ];
+
         yield 'minimal fake regex' => [
             '////',
             false,