feat: add git-dark theme (#303)

Author: Андрей Кожев

docs/themes.md

@@ -89,6 +89,7 @@ You can also try out and customize these themes on the [Demo Site](https://githu
 |        `android-dark`         | ![image](https://user-images.githubusercontent.com/20955511/183303685-fed30ead-2660-48bc-b724-04fe3c394c7f.png)  |
 | `deuteranopia-friendly-theme` | ![image](https://user-images.githubusercontent.com/107488620/183304765-9d423ff4-52ed-4a27-8a1c-2bcd290f4803.png) |
 |        `windows-dark`         | ![image](https://user-images.githubusercontent.com/103951737/183449796-23096f23-54b5-45af-8078-b8afd4f3baf3.png) |
+|          `git-dark`           | ![image](https://user-images.githubusercontent.com/103951737/183690748-060943ff-7b39-4229-b32d-806d654bd12d.png) |
 
 ### Can't find the theme you like?
 

src/themes.php

@@ -998,4 +998,16 @@
         "sideLabels" => "#00A4EF",
         "dates" => "#00A4EF",
     ],
+    "git-dark" => [
+        "background" => "#000000",
+        "border" => "#F05033",
+        "stroke" => "#F05033",
+        "ring" => "#F05033",
+        "fire" => "#F05033",
+        "currStreakNum" => "#F05033",
+        "sideNums" => "#F05033",
+        "currStreakLabel" => "#F05033",
+        "sideLabels" => "#F05033",
+        "dates" => "#F05033",
+    ],
 ];