tests(checker): make JSON decoding match implementation

Signed-off-by: Josh <[email protected]>

Author: joshtrichards

tests/lib/IntegrityCheck/CheckerTest.php

@@ -545,8 +545,8 @@ public function testVerifyCoreSignatureWithValidModifiedHtaccessSignatureData():
 	 */
 	public function testVerifyCoreSignatureWithModifiedMimetypelistSignatureData(): void {
 		$this->addTypicalStubs();
-		$shippedMimetypeAliases = (array)json_decode(file_get_contents(\OC::$SERVERROOT . '/resources/config/mimetypealiases.dist.json'));
-		$shippedMimetypeNames = (array)json_decode(file_get_contents(\OC::$SERVERROOT . '/resources/config/mimetypenames.dist.json'));
+		$shippedMimetypeAliases = (array)json_decode(file_get_contents(\OC::$SERVERROOT . '/resources/config/mimetypealiases.dist.json'), true);
+		$shippedMimetypeNames = (array)json_decode(file_get_contents(\OC::$SERVERROOT . '/resources/config/mimetypenames.dist.json'), true);
 		$allAliases = array_merge($shippedMimetypeAliases, ['my-custom/mimetype' => 'custom']);
 		$allMimetypeNames = array_merge($shippedMimetypeNames, ['my-custom/mimetype' => 'Custom Document']);