UI: Mark some strings translatable

- Listen to your mic
- Icon by
- Changelog

src/gtk/main-menu.ui

@@ -11,7 +11,7 @@
                 <attribute name="action">app.opendebuglog</attribute>
             </item>
             <item>
-                <attribute name="label" translatable="no">Changelog</attribute>
+                <attribute name="label" translatable="yes">Changelog</attribute>
                 <attribute name="action">app.open_changelog</attribute>
             </item>
             <item>

src/main.py

@@ -99,7 +99,7 @@ def on_about_action(self, widget, k):
             application_name='Whisper',
             website='https://github.com/mijorus/whisper',
             issue_url='https://github.com/mijorus/whisper/issues',
-            comments='Listen to your mic',
+            comments=_('Listen to your mic'),
             application_icon='it.mijorus.whisper',
             developer_name='Lorenzo Paderi',
             version=self.version,
@@ -108,7 +108,7 @@ def on_about_action(self, widget, k):
         )
 
         about.set_translator_credits(_("translator_credits"))
-        about.add_credit_section('Icon by', ['Jakub Steiner (jimmac)'])
+        about.add_credit_section(_('Icon by'), ['Jakub Steiner (jimmac)'])
 
         about.present()