update w.r.t. conference program

.gitlab/issue_templates/talk_without_paper.md

@@ -13,7 +13,7 @@
 - Conference Dates: <Start date DD/MM/YYYY - End date DD/MM/YYYY>
 - Conference Format: < Online | Hybrid | On-site >  
 - Conference Type: < Scientific Audience | Non-Scientific Audience >  
-- Conference Website: < URL, **required** and must provide online program >  
+- Conference Website: < URL >  
 - Language: < English >  
 - Keywords: < List, of, comma, separated, keywords >  
 - Research projects (Name of related research projects including + funding IDs):
@@ -26,3 +26,4 @@
 - Invited: < no | yes + proof via PDF attachment >     
 - File attachments:
     - Proof of invitation as PDF: **INVITATION.PDF**  
+    - Conference program as PDF (if not available via *Conference Website*) : **PROGRAM.PDF**