Minor dashboard tweaks, fix flex-list margins (#26829)

Some small dashboard tweaks:

- Remove margin-bottom from divider so first item does not appear to
have un-equal margins
- Restore previous icon color
- Add slight margin-right to icon

Before:
<img width="783" alt="Screenshot 2023-08-31 at 00 10 28"
src="https://github.com/go-gitea/gitea/assets/115237/b75f70d7-8704-4afb-866d-fea0484c52d4">

After:
<img width="783" alt="Screenshot 2023-08-31 at 00 10 08"
src="https://github.com/go-gitea/gitea/assets/115237/50ed0c47-6f7c-449e-a054-13091369d43f">

---------

Co-authored-by: wxiaoguang <wxiaoguang@gmail.com>

templates/repo/actions/runs_list.tmpl

@@ -1,4 +1,4 @@
-<div class="flex-list gt-m-0">
+<div class="flex-list">
 	{{if eq (len .Runs) 0}}
 	<div class="empty center">
 		{{svg "octicon-no-entry" 48}}

templates/repo/settings/deploy_keys.tmpl

@@ -11,7 +11,7 @@
 			</div>
 		</h4>
 		<div class="ui attached segment">
-			<div class="{{if not .HasError}}gt-hidden{{end}} gt-mb-4" id="add-deploy-key-panel">
+			<div class="{{if not .HasError}}gt-hidden{{end}}" id="add-deploy-key-panel">
 				<form class="ui form" action="{{.Link}}" method="post">
 					{{.CsrfTokenHtml}}
 					<div class="field">