bug(windows): keyboards with non-ascii letters in filename cannot be uninstalled

**Describe the bug**
On my Windows 10 computer, I created a new keyboard with Keyman Developer 11.0.1356. The keyboard file name contained a vowel with diacritics (ä). When I compiled the keyboard, Developer gave me a warning that I should not use these characters. But since it created the keybard I loaded it to Keyman Desktop and tried it out.
After that, I changed the file name, made some changes to the keyboard and loaded it again, and it worked.
The only issue is that the first trial keyboard, (the one with ä in the filename) is still installed in Keyman Desktop. I cannot remove it.
I tried uninstalling Keyman (using Revo Uninstaller to catch references in the registry), then rebooting and reinstalling Keyman Desktop and Developer. The link to the keyboard is still there.
I tried re-creating the keyboard file, and keyman actually links to the new version (I can see what has changed from that first trial version), but I still can’t remove it from Keyman Desktop.

Per Peter Knapp at https://community.software.sil.org/t/keyboard-cannot-be-uninstalled/2564

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**Keyman Desktop:**
- OS: Windows 10
- Keyman version: 11.0.1356.0

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**Keyboard**
- Keyboard name: foo_ä (for example)