Fix file extension of flag of Afghanistan

sources.csv

@@ -1,6 +1,6 @@
 File,Source,License,Modifications
 ug-flag-abkhazia.svg,https://commons.wikimedia.org/wiki/File:Flag_of_the_Republic_of_Abkhazia.svg,PD,
-ug-flag-afghanistan.png,https://en.wikipedia.org/wiki/File:Flag_of_the_Taliban.svg,PD,
+ug-flag-afghanistan.svg,https://en.wikipedia.org/wiki/File:Flag_of_the_Taliban.svg,PD,
 ug-flag-aland_islands.svg,https://commons.wikimedia.org/wiki/File:Flag_of_Aland_Islands.svg,PD,
 ug-flag-albania.svg,https://commons.wikimedia.org/wiki/File:Flag_of_Albania.svg,PD,
 ug-flag-algeria.svg,https://commons.wikimedia.org/wiki/File:Flag_of_Algeria.svg,PD,

src/data/main.csv

@@ -106,7 +106,7 @@ Sahrawi Arab Democratic Republic,"<img src=""ug-flag-sahrawi_arab_democratic_rep
 Zambia,"<img src=""ug-flag-zambia.svg"" />","<img src=""ug-map-zambia.png"" />","UG::Africa, UG::East_Africa, UG::Sovereign_State"
 Zimbabwe,"<img src=""ug-flag-zimbabwe.svg"" />","<img src=""ug-map-zimbabwe.png"" />","UG::Africa, UG::East_Africa, UG::Sovereign_State"
 Canary Islands,,"<img src=""ug-map-canary_islands.png"" />",UG::Africa
-Afghanistan,"<img src=""ug-flag-afghanistan.png"" />","<img src=""ug-map-afghanistan.png"" />","UG::Asia, UG::Sovereign_State"
+Afghanistan,"<img src=""ug-flag-afghanistan.svg"" />","<img src=""ug-map-afghanistan.png"" />","UG::Asia, UG::Sovereign_State"
 Bahrain,"<img src=""ug-flag-bahrain.svg"" />","<img src=""ug-map-bahrain.png"" />","UG::Asia, UG::Middle_East, UG::Sovereign_State"
 Bangladesh,"<img src=""ug-flag-bangladesh.svg"" />","<img src=""ug-map-bangladesh.png"" />","UG::Asia, UG::Sovereign_State"
 Bhutan,"<img src=""ug-flag-bhutan.svg"" />","<img src=""ug-map-bhutan.png"" />","UG::Asia, UG::Sovereign_State"