fix: failed connectionless present proof on some case

In demo menu (2a) connectionless proof request, If a mobile agent (for instance Trinsic) does not include Accept header when present proof request, the demo would fail.

Signed-off-by: kukgini <kukgini@users.noreply.github.com>
Signed-off-by: Ry Jones <ry@linux.com>

Author: kukgini

demo/runners/support/agent.py

@@ -781,7 +781,7 @@ async def _send_connectionless_proof_req(self, request: ClientRequest):
             return web.Response(status=404)
         proof_reg_txn = proof_exch["presentation_request_dict"]
         proof_reg_txn["~service"] = await self.service_decorator()
-        if request.headers["Accept"] == "application/json":
+        if request.headers.get("Accept") == "application/json":
             return web.json_response(proof_reg_txn)
         objJsonStr = json.dumps(proof_reg_txn)
         objJsonB64 = base64.b64encode(objJsonStr.encode("ascii"))