Fix failing test on Travis CI

Chalk disables colors in CI environments, making the test pass locally
but not on Travis CI.

This also makes the snapshot more readable.

tests_integration/__tests__/__snapshots__/write.js.snap

@@ -2,8 +2,8 @@
 
 exports[`do not write file with --write + invalid file 1`] = `
 "invalid.js: SyntaxError: Unexpected token, expected ; (1:6)
-> 1 | this is invalid!
-    |      ^
+> 1 | this is invalid!
+    |      ^
 "
 `;
 

tests_integration/__tests__/write.js

@@ -17,7 +17,11 @@ test("do not write file with --write + formated file", () => {
 });
 
 test("do not write file with --write + invalid file", () => {
-  const result = runPrettier("cli/write", ["--write", "invalid.js"]);
+  const result = runPrettier("cli/write", [
+    "--write",
+    "invalid.js",
+    "--no-color"
+  ]);
 
   expect(result.stderr).toMatchSnapshot();
   expect(result.write).toHaveLength(0);