Update One Light modified color (#12143)

Release Notes:

- Changed the `modified` color on the one-light color theme to a more
readable value

The current color in the file tree for modified files is basically
unreadable in the default light mode
<img width="238" alt="image"
src="https://github.com/zed-industries/zed/assets/50590465/e553673f-1c24-41d9-b1b9-1dbbb7419d1e">

This change just changes the color to match that of the one-light theme
present in vscode
~~old proposal:
https://github.com/zed-industries/zed/assets/50590465/b4dc4030-bcd8-429a-84b8-2744e213e492~~
new proposal:
<img width="378" alt="image"
src="https://github.com/zed-industries/zed/assets/50590465/41c53019-8cf3-4927-9879-47937388cde8">

This does have a side-effect of changing the modified color on the side
in the editor, but personally I think this change is negligable.

assets/themes/one/one.json

@@ -491,7 +491,7 @@
         "info": "#5c78e2ff",
         "info.background": "#e2e2faff",
         "info.border": "#cbcdf6ff",
-        "modified": "#dec184ff",
+        "modified": "#a47a23ff",
         "modified.background": "#faf2e6ff",
         "modified.border": "#f4e7d1ff",
         "predictive": "#9b9ec6ff",