- Use TXT records in order to determine the latest available version.
- This addresses a valid privacy issue, as with HTTP requests the server
can keep track(estimated) of how many instances are using Forgejo, with
DNS that's basically not possible as the server will never receive any
data, as the only ones receiving data are DNS resolvers.
- Don't use `ioutil` package anymore as it doesn't anything special
anymore since Go 1.16:
```
// As of Go 1.16, the same functionality is now provided
// by package io or package os, and those implementations
// should be preferred in new code.
```
Co-authored-by: Lunny Xiao <xiaolunwen@gmail.com>
We have the `AppState` module now, it can store app related data easily. We do not need to create separate tables for each feature.
So the update checker can use `AppState` instead of a one-row dedicate table.
And the code of update checker is moved from `models` to `modules`.
