Fix create repository page's help text

- Fix a regression from go-gitea#20458, whereby the introduced CSS was
targeting the help text of the repository creation page. Specify the captcha
field by adding a new class to the `<div>`.
- Resolves go-gitea#20808

Author: Gusted

templates/user/auth/signup_inner.tmpl

@@ -55,7 +55,7 @@
 					</div>
 				{{end}}
 				{{if and .EnableCaptcha (eq .CaptchaType "mcaptcha")}}
-					<div class="inline field df ac db-small">
+					<div class="inline field df ac db-small captcha-field">
 						<span>{{.locale.Tr "captcha"}}</span>
 						<div class="border-secondary w-100-small" id="mcaptcha__widget-container" style="width: 50%; height: 5em"></div>
 						<div class="m-captcha" data-sitekey="{{ .McaptchaSitekey }}" data-instance-url="{{ .McaptchaURL }}"></div>

web_src/less/_form.less

@@ -157,7 +157,7 @@ textarea:focus,
       }
 
       .inline.field > label,
-      .inline.field > span {
+      .inline.field.captcha-field > span {
         text-align: right;
         width: @create-page-form-input-padding;
         word-wrap: break-word;