[FIX] project: Fix customer salutation in rating email

If there isn't any customer set on the task, the current behavior
will display 'Hello False,' in salutation rating email as intro.

This commit will fix it by display only 'Hello,' if there isn't
any customer set.

Task ID 2238816

closes odoo/odoo#50366

X-original-commit: e7b71c6e497aa8d823181440333f371f1da5ade8
Signed-off-by: Yannick Tivisse (yti) <yti@odoo.com>

addons/project/data/project_mail_template_data.xml

@@ -38,7 +38,11 @@
     <table border="0" cellpadding="0" cellspacing="0" width="590" style="width:100%; margin:0px auto;">
     <tbody>
         <tr><td valign="top" style="font-size: 13px;">
-            Hello ${partner.name},<br/><br/>
+            % if partner.name:
+                Hello ${partner.name},<br/><br/>
+            % else:
+                Hello,<br/><br/>
+            % endif
             Please take a moment to rate our services related to the task "<strong>${object.name}</strong>"
             % if object.rating_get_rated_partner_id().name:
                 assigned to <strong>${object.rating_get_rated_partner_id().name}</strong>.<br/>