Log Message:
varnish: update to 7.2.1

Security
  fixes VSV00011 Varnish HTTP/2 Request Forgery Vulnerability
VEXT
  Support Varnish Extensions
Parameters
  Duration values (with a unit in seconds) can optionally take a duration unit
Other changes in varnishd
  The metadata VMODs exposes to Varnishd has changed to a non-binary format
Changes to VCL
  ESI sub-requests can no longer inherit req.http.transfer-encoding
Bundled VMODs
  std: add std.now() and std.timed_call()
  cookie: generated headers no longer have a spurious trailing semi-colon
varnishlog
  The Begin log records may contain a 4th field with the sub-level of sub-tasks.
  The -k option from varnishlog is now available in varnishncsa.
varnishstat
  MAIN.fetch_no_thread renamed to MAIN.bgfetch_no_thread
  MAIN.shm_bytes added