Update ReadableSpan.to_json indent argument type

[hennie-the-barbarian]

Description

Changed the type of the indent argument in ReadableSpan to match the type signature of json.dumps, since indent is simply being passed through to json.dumps

Fixes # N/A

Type of change

Please delete options that are not relevant.

• Bug fix (non-breaking change which fixes an issue)

How Has This Been Tested?

TBD as it's a simple change

• Test that if fixes linting when passing an indent value of None to to_json

Does This PR Require a Contrib Repo Change?

No

Answer the following question based on these examples of changes that would require a Contrib Repo Change:

• The OTel specification has changed which prompted this PR to update the method interfaces of opentelemetry-api/ or opentelemetry-sdk/

• The method interfaces of test/util have changed

• Scripts in scripts/ that were copied over to the Contrib repo have changed

• Configuration files that were copied over to the Contrib repo have changed (when consistency between repositories is applicable) such as in

  • pyproject.toml
  • isort.cfg
  • .flake8

• When a new .github/CODEOWNER is added

• Major changes to project information, such as in:

  • README.md
  • CONTRIBUTING.md

• Yes. - Link to PR:

• No.

Checklist:

• Followed the style guidelines of this project
• Changelogs have been updated
• Unit tests have been added
• Documentation has been updated

[linux-foundation-easycla]

• ✅login: hennie-the-barbarian / (8779b01)

The committers listed above are authorized under a signed CLA.

[rbtz-openai]

1. The current target python version is 3.8, you'll need to use Optional until we switch to something that supports https://peps.python.org/pep-0604/
2. There are a lot of to_json functions around the codebase, which all currently share the same signature, which makes it "kind of" an interface, so I would say it should be a "none or all" type of a change.

I'm not a maintainer, so take it with a grain of salt.

[xrmx]

The codebase uses Optional[int]