feat: Add videos of 2023 pyhf Users and Developers Workshop

* Add links to YouTube recordings of Alex Held and Mason Proffitt's talks
  at the 2023 pyhf Users and Developers Workshop at CERN.
   - c.f. https://youtu.be/hrs0EpceO_8
   - c.f. https://youtu.be/EaNwmH_dTAc

Author: matthewfeickert

_data/people/alexander-held.yml

@@ -454,6 +454,7 @@ presentations:
   - title: "Constructing and steering pyhf models with cabinetry"
     date: 2023-12-04
     url: https://indico.cern.ch/event/1294577/contributions/5689564/
+    video: https://youtu.be/hrs0EpceO_8
     meeting: pyhf Users and Developers Workshop 2023
     meetingurl: https://indico.cern.ch/event/1294577/
     location: "CERN"

_data/people/masonproffitt.yml

@@ -176,6 +176,7 @@ presentations:
   - title: "abcd_pyhf: Likelihood-based ABCD method for background estimation and hypothesis testing with pyhf"
     date: 2023-12-04
     url: https://indico.cern.ch/event/1294577/contributions/5700251/
+    video: https://youtu.be/EaNwmH_dTAc
     meeting: pyhf Users and Developers Workshop 2023
     meetingurl: https://indico.cern.ch/event/1294577/
     location: CERN