Use a transparent SCMM logo in plugin center (#1936)

This replaces the SCM-Manager logo for the plugins
without own icons with a version with a transparent
background to make it less intense in dark themes.

gradle/changelog/plugin_center_logo.yaml

@@ -0,0 +1,2 @@
+- type: changed
+  description: SCM-Manager icon in the plugin center has a transparent background ([#1936](https://github.com/scm-manager/scm-manager/pull/1936))

scm-ui/ui-webapp/src/admin/plugins/components/PluginAvatar.tsx

@@ -50,7 +50,7 @@ export default class PluginAvatar extends React.Component<Props> {
             plugin
           }}
         >
-          <Image src={plugin.avatarUrl ? plugin.avatarUrl : "/images/blib.jpg"} alt="Logo" />
+          <Image src={plugin.avatarUrl ? plugin.avatarUrl : "/images/blibTransparentBG.png"} alt="Logo" />
         </ExtensionPoint>
       </BoundingBox>
     );