docs: Fix garden screenshot to be consistent size (DenverCoder1#273)

Author: DenverCoder1

docs/themes/README.md

@@ -80,7 +80,7 @@ You can also try out and customize these themes on the [Demo Site](https://githu
 |        `leafy`         | ![image](https://user-images.githubusercontent.com/69510006/146630969-ff7bc045-518e-43c0-83df-2d275f3e4b1d.jpg) |
 |      `navy-gear`       | ![image](https://user-images.githubusercontent.com/20955511/153954354-60438cfa-d0a0-4737-936c-65b61faf637d.png) |
 |        `hacker`        | ![image](https://user-images.githubusercontent.com/20955511/164965194-724816b5-5aa0-4c36-8bae-f3cbafd2c2a4.png) |
-|        `garden`        | ![image](https://user-images.githubusercontent.com/44000014/165035015-153d9b3a-bd3a-4e34-b252-3c64ab081b75.png) |
+|        `garden`        | ![image](https://user-images.githubusercontent.com/20955511/177458181-5c2242f0-1c89-4de0-9965-28c777f9f8d7.png) |
 | `github-green-purple`  | ![image](https://user-images.githubusercontent.com/20955511/173238945-f572fdfb-dbf6-4141-8ee6-b70f6186548e.png) |
 
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