chore: Update translations (#1561)

Co-authored-by: Pranav Raj S <pranav@chatwoot.com>
Co-authored-by: Yovan Lutfi Arya (Regerta)
Co-authored-by: Goudarz Jafari (Goudarz)
Co-authored-by: korho
Co-authored-by: vfasoulas

app/javascript/dashboard/i18n/locale/cs/conversation.json

@@ -24,6 +24,7 @@
     "REPLYING_TO": "Odpovídáte uživateli:",
     "REMOVE_SELECTION": "Odstranit výběr",
     "DOWNLOAD": "Stáhnout",
+    "UPLOADING_ATTACHMENTS": "Uploading attachments...",
     "HEADER": {
       "RESOLVE_ACTION": "Vyřešit",
       "REOPEN_ACTION": "Znovu otevřít",