Zola 0.19.0 doesn't accept all valid YAML dates

[kytta]

Bug Report

With 0.19.0, Zola can now understand more date formats. However, I believe there is a bug in the implementation which makes the millisecond separator (but not the milliseconds) required

Environment

Zola version: 0.19.0

Expected Behavior

2024-06-22 18:42:00 +02:00 should be a correct datetime

Current Behavior

Error: Failed to build the site
Error: Error when parsing front matter of section `path/to/file.md`
Error: Reason: YAML deserialize error: Error("Unable to parse datetime", line: 2, column: 1)

If I add a single dot after the seconds (2024-06-22 18:42:00. +02:00), the issue goes away.

Step to reproduce

1. Create a Markdown file with a date like 2024-06-22 18:42:00 +02:00
2. Try to zola build or zola serve
3. Observe the error

Possible solution

I believe there is an error in the regex:

https://github.com/getzola/zola/blob/v0.19.0/components/utils/src/de.rs#L12

As you can see, the millisecond (aka fraction) part of the string is optional, but the period is not. This contradicts the YAML Working Draft on Timestamp which was mentioned in the original issue.

-    let re = Regex::new(r#"^"?([0-9]{4})-([0-9][0-9]?)-([0-9][0-9]?)([Tt]|[ \t]+)([0-9][0-9]?):([0-9]{2}):([0-9]{2})\.([0-9]*)?Z?([ \t]([-+][0-9][0-9]?)(:([0-9][0-9]?))?Z?|([-+][0-9]{2})?:([0-9]{2})?)?|([0-9]{4})-([0-9]{2})-([0-9]{2})"?$"#).unwrap();
+    let re = Regex::new(r#"^"?([0-9]{4})-([0-9][0-9]?)-([0-9][0-9]?)([Tt]|[ \t]+)([0-9][0-9]?):([0-9]{2}):([0-9]{2})(?:\.([0-9]*))?Z?([ \t]([-+][0-9][0-9]?)(:([0-9][0-9]?))?Z?|([-+][0-9]{2})?:([0-9]{2})?)?|([0-9]{4})-([0-9]{2})-([0-9]{2})"?$"#).unwrap();

Additional info

Same error also happens if I omit the seconds altogether (2024-06-22 18:42 +02:00). I may be opinionated, but I think requiring those should be optional, too.

Relates to #2071, #2208

[Keats]

Can you submit the change as a PR with some additional tests?

[kytta]

@Keats will do :) would you also be interested in using named regex groups instead of indexed ones? I find it more readable and more flexible

[Keats]

Sure go for it