Go's semantic import versioning requires v2+ modules to include the
major version in the module path. This enables using proper version
tags (v3.x.x) instead of pseudo-versions.
Updated module path: code.gitcaddy.com/server/v3
Update all go tool dependencies to latest version. WIP because I think
there are new gopls errors, would like to confirm them on CI first. Here
is from a local run:
```
modules/markup/markdown/goldmark.go:115:37-53: unnecessary type arguments
modules/markup/html.go:45:32-49: unnecessary type arguments
modules/markup/internal/renderinternal.go:20:33-49: unnecessary type arguments
modules/markup/common/linkify.go:27:32-49: unnecessary type arguments
modules/util/time_str.go:28:39-63: unnecessary type arguments
routers/web/repo/pull.go:704:19: impossible condition: non-nil == nil
modules/util/util_test.go:248:14-23: unused parameter: other
```
~~Backport because the `gxz` update might have security benefits.~~
Remove unmaintainable sanitizer rules. No need to add special "class"
regexp rules anymore, use RenderInternal.SafeAttr instead, more details
(and examples) are in the tests
