Clean up CI jobs (#4606)

Remove PCH as an option - it's now always disabled for all jobs

Disable LTO in the Windows build

Merge the Ubuntu Qt 6.2.4 & Ubuntu plugin build

Only upload a single macOS job into the nightly release, and clearly mark it as a macOS 10.15 build.

src/providers/seventv/SeventvBadges.hpp

@@ -9,6 +9,7 @@
 #include <memory>
 #include <shared_mutex>
 #include <unordered_map>
+#include <vector>
 
 namespace chatterino {
 

src/providers/twitch/TwitchAccount.hpp

@@ -15,6 +15,7 @@
 #include <functional>
 #include <mutex>
 #include <set>
+#include <vector>
 
 namespace chatterino {