[FIX] mail: chatter, planned activities badge spacing

Prior to this commit, in the "Chatter", when a user planned an activity,
a new section appeared at the top of the chatter displaying the planned
activities. Users had the ability to collapse this section. When the
section was collapsed, a title and a badge were displayed next to it,
indicating the number of activities.

However, since milk, it was observed that the badge was positioned too
close to the title, requiring some spacing adjustments. Additionally,
the badge has been updated to adhere to milk by adopting a rounded-pill
shape.

task-3339256
part of task-3326263

closes odoo/odoo#122945

X-original-commit: fab1f6242cc0d8984a5f36876dcbf4150c340d8d
Signed-off-by: Alexandre Kühn (aku) <aku@odoo.com>

addons/mail/static/src/web/chatter.xml

@@ -132,7 +132,7 @@
             <div class="d-flex align-items-center px-3">
                 <i class="fa fa-fw" t-att-class="state.showActivities ? 'fa-caret-down' : 'fa-caret-right'"/>
                 Planned Activities
-                <span t-if="!state.showActivities" class="badge text-bg-success"><t t-esc="activities.length"/></span>
+                <span t-if="!state.showActivities" class="badge rounded-pill ms-2 text-bg-success"><t t-esc="activities.length"/></span>
             </div>
             <hr class="flex-grow-1"/>
         </div>