test: remove accidental hard tab

test/incremental/delete_comptime_decls

@@ -31,7 +31,7 @@ pub fn main() void {}
 comptime {
     const x: [*c]u8 = null;
     var runtime_len: usize = undefined;
-		runtime_len = 0;
+    runtime_len = 0;
     const y = x[0..runtime_len];
     _ = y;
 }