With issue 1465 on openapi-generator [1] being fixed, we can not extract
shared properties of the gettable and postable alert definition into a
shared object (`alert`) like we do for silence, gettable silence and
postable silence.
In addition this patch does the following changes to the UI:
- Use `List GettableAlert` instead of plural type definition like
`GettableAlerts` because the plural definitions are not generated.
- Fix openapi-generator-cli docker image to specific hash.
[1] https://github.com/OpenAPITools/openapi-generator/issues/1465
Signed-off-by: Max Leonard Inden <IndenML@gmail.com>
Max Leonard Inden