Fix wrong og:image path (#2099)

## Description:

The OpenGraph image in index.html was pointing to
/resources/images/GameplayScreenshot.png, which does not exist.
Updated to /images/GameplayScreenshot.png so that preview thumbnails
display correctly on social platforms.

## Please complete the following:

- [x] I have added screenshots for all UI updates
- [x] I process any text displayed to the user through translateText()
and I've added it to the en.json file
- [x] I have added relevant tests to the test directory
- [x] I confirm I have thoroughly tested these changes and take full
responsibility for any bugs introduced

## Please put your Discord username so you can be contacted if a bug or
regression is found:

aotumuri

src/client/index.html

@@ -30,7 +30,7 @@
     />
     <meta
       property="og:image"
-      content="https://openfront.io/resources/images/GameplayScreenshot.png"
+      content="https://openfront.io/images/GameplayScreenshot.png"
     />
     <meta property="og:type" content="game" />