minor symfony#57260 [Mime] fix test (xabbuh)

This PR was merged into the 7.2 branch.

Discussion
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[Mime] fix test

| Q             | A
| ------------- | ---
| Branch?       | 7.2
| Bug fix?      | no
| New feature?  | no
| Deprecations? | no
| Issues        |
| License       | MIT

Commits
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2f74ec6 fix test

Author: xabbuh

src/Symfony/Component/Mime/Tests/Part/TextPartTest.php

@@ -101,7 +101,7 @@ public function testCustomEncoderNeedsToRegisterFirst()
     public function testOverwriteDefaultEncoder()
     {
         $this->expectException(InvalidArgumentException::class);
-        $this->expectExceptionMessage('You are not allowed to change the default encoders ("quoted-printable","base64","8bit"). If you want to modify their behaviour please register and use a new encoder.');
+        $this->expectExceptionMessage('You are not allowed to change the default encoders ("quoted-printable", "base64", and "8bit").');
         TextPart::addEncoder('8bit', $this->createMock(ContentEncoderInterface::class));
     }