[FIX] web: remove whitespace below report iframe

This commit removes whitespace below iframes in reports, which also caused an
unnecessary vertical scrollbar to appear.

task-3334745

closes odoo/odoo#122052

Signed-off-by: Bruno Boi (boi) <boi@odoo.com>

addons/web/static/src/webclient/actions/reports/report_action.xml

@@ -7,7 +7,7 @@
                 <t t-set-slot="control-panel-create-button">
                     <button t-on-click="print" type="button" class="btn btn-primary" title="Print">Print</button>
                 </t>
-                <iframe t-ref="iframe" t-on-load="onIframeLoaded" class="h-100 w-100" t-att-src="reportUrl" />
+                <iframe t-ref="iframe" t-on-load="onIframeLoaded" class="h-100 w-100 d-block" t-att-src="reportUrl" />
             </Layout>
         </div>
     </t>