update countries.json (#651)

## Description:
Update countries.json, remove duplicate flags, fix flags
## Please complete the following:

- [ ] I have added screenshots for all UI updates
- [ ] I confirm I have thoroughly tested these changes and take full
responsibility for any bugs introduced
- [ ] I understand that submitting code with bugs that could have been
caught through manual testing blocks releases and new features for all
contributors

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

<DISCORD USERNAME>

---------

Co-authored-by: evan <openfrontio@gmail.com>

src/client/data/countries.json

@@ -1674,10 +1674,6 @@
     "continent": "Africa",
     "name": "Republic of the Congo"
   },
-  {
-    "code": "cthulhu_republic",
-    "name": "Republic of Cthulhu"
-  },
   {
     "code": "Republic of Egypt",
     "continent": "Africa",