chore: upgrade go-swagger to v0.35.0 and enforce zero swagger warnings (#38299)

Updates `go-swagger` to v0.35.0 and makes swagger generation and
validation warning-free, with the build now failing on any warning
(`go-swagger` itself exits `0` on warnings).

- Generation passes `--enable-allof-compounding` (keeps `$ref` fields
bare, no spec change) and `--skip-enum-desc` (drops the enum description
that duplicates `x-go-enum-desc` and was the only source of `allOf`
noise in the OpenAPI 3.0 output).
- Fixed warnings at the source: dropped `swagger:strfmt` where it
conflicts with `required: true` (`required` kept, `time.Time` still maps
to `date-time`), fixed a malformed `units_map` example, moved the
`parameterBodies` injection hack to `swagger:parameters`, and removed
unused responses.

Fixes: https://github.com/go-gitea/gitea/issues/12508

---------

Co-authored-by: bircni <bircni@icloud.com>

modules/structs/issue.go

@@ -133,7 +133,6 @@ type IssueAssigneesOption struct {
 // EditDeadlineOption options for creating a deadline
 type EditDeadlineOption struct {
 	// required:true
-	// swagger:strfmt date-time
 	Deadline *time.Time `json:"due_date"`
 }