fix: add missing call to writeColon in JSONWriter.writeNameValue

[mpfaff]

What this PR does / why we need it?

See #3224:

The implementation of JSONWriter.writeNameValue is broken. It is missing a call to writeColon between the writeName and writeAny.

Summary of your change

Add the aforementioned missing call, fixing the issue.

Please indicate you've done the following:

• Made sure tests are passing and test coverage is added if needed.
• Made sure commit message follow the rule of Conventional Commits specification.
• Considered the docs impact and opened a new docs issue or PR with docs changes if needed.

If I recall correctly, I tried running tests at the time I implemented this fix but they failed due to (seemingly) relying on the host system having a particular time zone.

[CLAassistant]

Thank you for your submission! We really appreciate it. Like many open source projects, we ask that you sign our Contributor License Agreement before we can accept your contribution.
_{You have signed the CLA already but the status is still pending? Let us recheck it.}

[wenshao]

请签署CLA