Go 1.22 support

[hanzo]

Describe the bug
I'm running into issues with Athens when trying to download modules that specify go 1.22 as their go directive.

Error Message

When running Athens on an image with Go 1.21 installed, I see the following error when Athens tries to download a module that specifies go 1.22 as its go directive:

```console
exit status 1: go: loading module retractions for github.com/foo/bar@v1.2.0: module github.com/foo/bar@v1.2.0 requires go >= 1.22 (running go 1.21.7)
```

When running Athens on an image with Go 1.22 installed, the previous error does not occur but the performance of Athens is severely degraded. When a single repo makes a series of requests to Athens (e.g. by running go mod tidy from a fresh clone) I'm seeing CPU spike to 80-90% and it takes a few minutes to download dependencies, while the same operation previously took less than a minute.

To Reproduce
Steps to reproduce the behavior:
Call Athens proxy to download any go module with go 1.22 in its go directive, e.g. https://github.com/achille-roussel/sqlrange/blob/d51fe227ca2014e7c14492acbf1e59fc6c514a41/go.mod#L3

Environment (please complete the following information):

• OS: Linux 64bit
• Go version : 1.21.7 and 1.22.1
• Proxy version : v0.13.1
• Storage (fs/mongodb/s3 etc.) : s3

[matt0x6F]

Hey, I wasn't able to reproduce this locally. I ran 0.13.1 built with Go 1.20 in my test setup and saw these logs:

dev-1  |        http-method=GET http-path=/github.com/@v/list request-id=61c9dab1-7e97-4fa5-ac91-b99020f7cb3f 
dev-1  | INFO[12:09AM]: incoming request        http-method=GET http-path=/github.com/@v/list http-status=404 request-id=61c9dab1-7e97-4fa5-ac91-b99020f7cb3f 
dev-1  | INFO[12:09AM]: incoming request        http-method=GET http-path=/github.com/matt0x6f/athens-test-repo/@v/list http-status=200 request-id=951c6c55-7edb-4e88-948d-a18e69fa871c 
dev-1  | INFO[12:09AM]: incoming request        http-method=GET http-path=/github.com/matt0x6f/athens-test-repo/@latest http-status=200 request-id=dc04a71a-9816-4fbc-be2b-c977b6efde56 

Here's my test remote repository: https://github.com/matt0x6F/athens-test-repo/
Here's my test local repository: https://github.com/matt0x6F/athens-local (notice .vscode/settings.json)

[matt0x6F]

Closing this issue due to inactivity. Reopen if you've got updates.