test: fix tests/source/issue-1278.rs test header

jieyouxu · ytmimi · commit 5e937e0800ac · 2025-10-08T15:27:46.000-04:00
`key = value` is not a valid significant test comment form, the value
must be `Block` not double-quoted `"block"` or `"Block"`.
diff --git a/tests/source/issue-1278.rs b/tests/source/issue-1278.rs
@@ -1,4 +1,4 @@
-// rustfmt-indent_style = "block"
+// rustfmt-indent_style: Block
 
 #![feature(pub_restricted)]
 
diff --git a/tests/target/issue-1278.rs b/tests/target/issue-1278.rs
@@ -1,4 +1,4 @@
-// rustfmt-indent_style = "block"
+// rustfmt-indent_style: Block
 
 #![feature(pub_restricted)]
 
