Improve flex ellipsis (#30479)

![image](https://github.com/go-gitea/gitea/assets/2114189/857794d8-2170-42be-a5bf-47ebacbafebd)

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Co-authored-by: silverwind <me@silverwind.io>

web_src/css/modules/label.css

@@ -5,6 +5,8 @@
   display: inline-flex;
   align-items: center;
   gap: .25rem;
+  min-width: 0;
+  max-width: 100%; /* since we are using "flex" to align label contents, we also need to limit the x-axis, a label shouldn't be wider than 100% */
   vertical-align: middle;
   line-height: 1;
   background: var(--color-label-bg);