Make this code compatible with PHP 7.3.

See https://externals.io/message/102147 for details.

Author: sebastianbergmann

tests/ParserTest.php

@@ -75,15 +75,15 @@ public function testParseWithMultipleChunks(): void
 
     public function testParseWithRemovedLines(): void
     {
-        $content = <<<A
+        $content = <<<END
 diff --git a/Test.txt b/Test.txt
 index abcdefg..abcdefh 100644
 --- a/Test.txt
 +++ b/Test.txt
 @@ -49,9 +49,8 @@
  A
 -B
-A;
+END;
         $diffs = $this->parser->parse($content);
         $this->assertInternalType('array', $diffs);
         $this->assertContainsOnlyInstancesOf(Diff::class, $diffs);
@@ -118,7 +118,7 @@ public function testParseWithRemovedLines(): void
 
     public function testParseDiffForMulitpleFiles(): void
     {
-        $content = <<<A
+        $content = <<<END
 diff --git a/Test.txt b/Test.txt
 index abcdefg..abcdefh 100644
 --- a/Test.txt
@@ -134,7 +134,7 @@ public function testParseDiffForMulitpleFiles(): void
 @@ -1,2 +1,3 @@
  A
 +B
-A;
+END;
         $diffs = $this->parser->parse($content);
         $this->assertCount(2, $diffs);