Date YAML is processed before shortcode is evaluated

Bug description

It seems the date YAML is processed before the shortcode is evaluated.

Steps to reproduce

For index.qmd:

---
title: "{{< var date >}}"
date: "{{< var date >}}"
---

_variables.yml

date: 2024/04/19

Expected behavior

The result should be the same as below:

---
title: "{{< var date >}}"
date: "2024/04/19"
---

Actual behavior

Results in Invalid Date

Your environment

• IDE: RStudio 2023.12.1+402 (2023.12.1+402)
• OS: MacOS Sonoma 14.4.1

Quarto check output

Quarto 1.5.30
[✓] Checking versions of quarto binary dependencies...
Pandoc version 3.1.13: OK
Dart Sass version 1.70.0: OK
Deno version 1.41.0: OK
Typst version 0.11.0: OK
[✓] Checking versions of quarto dependencies......OK
[✓] Checking Quarto installation......OK
Version: 1.5.30
Path: /Applications/quarto/bin

[✓] Checking tools....................OK
TinyTeX: (not installed)
Chromium: (not installed)

[✓] Checking LaTeX....................OK
Using: Installation From Path
Path: /Library/TeX/texbin
Version: 2023

[✓] Checking basic markdown render....OK

[✓] Checking Python 3 installation....OK
Version: 3.9.6
Path: /Users/emitanaka/.virtualenvs/r-reticulate/bin/python3
Jupyter: (None)

  Jupyter is not available in this Python installation.
  Install with python3 -m pip install jupyter

[✓] Checking R installation...........OK
Version: 4.3.3
Path: /Library/Frameworks/R.framework/Resources
LibPaths:
- /Library/Frameworks/R.framework/Versions/4.3-arm64/Resources/library
knitr: 1.45
rmarkdown: 2.26

[✓] Checking Knitr engine render......OK