[bugfix] Fix invalid period parameter when generating the TOTP URL (#4536)

# Description

This MR removes the time unit `s` (for seconds) from the `period` parameter in the TOTP URL.

closes #4535

## Checklist

Please put an x inside each checkbox to indicate that you've read and followed it: `[ ]` -> `[x]`

If this is a documentation change, only the first checkbox must be filled (you can delete the others if you want).

- [x] I/we have read the [GoToSocial contribution guidelines](https://codeberg.org/superseriousbusiness/gotosocial/src/branch/main/CONTRIBUTING.md).
- [ ] I/we have discussed the proposed changes already, either in an issue on the repository, or in the Matrix chat.
- [x] I/we have not leveraged AI to create the proposed changes.
- [x] I/we have performed a self-review of added code.
- [x] I/we have written code that is legible and maintainable by others.
- [ ] I/we have commented the added code, particularly in hard-to-understand areas.
- [ ] I/we have made any necessary changes to documentation.
- [ ] I/we have added tests that cover new code.
- [ ] I/we have run tests and they pass locally with the changes.
- [ ] I/we have run `go fmt ./...` and `golangci-lint run`.

Co-authored-by: gruf <gruf@noreply.codeberg.org>
Reviewed-on: https://codeberg.org/superseriousbusiness/gotosocial/pulls/4536
Co-authored-by: TwizzyDizzy <codeberg@thomasdalichow.de>
Co-committed-by: TwizzyDizzy <codeberg@thomasdalichow.de>

internal/processing/user/twofactor.go

@@ -132,8 +132,8 @@ func (p *Processor) TwoFactorQRCodeURIGet(
 		RawQuery: encodeQuery(url.Values{
 			"secret":    {user.TwoFactorSecret},
 			"issuer":    {issuer},
-			"period":    {"30s"}, // 30s totp validity.
-			"digits":    {"6"},   // 6-digit totp.
+			"period":    {"30"}, // 30 seconds totp validity.
+			"digits":    {"6"},  // 6-digit totp.
 			"algorithm": {"SHA1"},
 		}),
 	}, nil