The workaround involves setting up a Text Replacement for the letter "i". To do this, go to Settings -> General -> Keyboard -> Text Replacement, and tap the plus (+) button. In the Phrase field, type an uppercase "I", and in the Shortcut field, type a lowercase "i". This should fix the problem until Apple addresses it properly in the next iOS update, which shouldn't be far off.
Preview at WWDC likely in June, followed by September launch.