fix: php-tuf#396 Update RollbackAttackException message (php-tuf#405)

Author: star-szr

src/Metadata/Verifier/RootVerifier.php

@@ -33,8 +33,8 @@ protected function checkRollbackAttack(MetadataBase $untrustedMetadata): void
         $expectedUntrustedVersion = $this->trustedMetadata->version + 1;
         $untrustedVersion = $untrustedMetadata->version;
         if ($expectedUntrustedVersion && ($untrustedMetadata->version !== $expectedUntrustedVersion)) {
-            throw new RollbackAttackException("Remote 'root' metadata version \"$$untrustedVersion\" " .
-              "does not the expected version \"$$expectedUntrustedVersion\"");
+            throw new RollbackAttackException("Remote 'root' metadata version \"{$untrustedVersion}\" " .
+              "does not match the expected version \"{$expectedUntrustedVersion}\"");
         }
         parent::checkRollbackAttack($untrustedMetadata);
     }

tests/Unit/Client/VerifierTest.php

@@ -120,7 +120,7 @@ public function verify(MetadataBase $untrustedMetadata): void
     public function testCheckRollbackAttackAttackExpectedVersion(): void
     {
         $this->expectException('\Tuf\Exception\Attack\RollbackAttackException');
-        $this->expectExceptionMessage('Remote \'root\' metadata version "$2" does not the expected version "$3"');
+        $this->expectExceptionMessage('Remote \'root\' metadata version "2" does not match the expected version "3"');
 
         // The incoming version is lower than the local version, so this should
         // be identified as a rollback attack.