Read and write with content type

[atimin]

Closes #

Please check if the PR fulfills these requirements

• Tests for the changes have been added (for bug fixes / features)
• Docs have been added / updated (for bug fixes / features)
• CHANGELOG.md have been updated (for bug fixes / features / docs)

What kind of change does this PR introduce?

Feautre

What is the current behavior?

Since version 1.3, ReductStore supports the Conten-Type header, but the SDK doesn't"t provide an API for this.

What is the new behavior?

No, you can write and read records with the content type:

    await bucket_1.write("entry-1", b"something", content_type="text/plain")

    async with bucket_1.read("entry-1") as record:
        data = await record.read_all()
        assert data == b"something"
        assert record.content_type == "text/plain"

Does this PR introduce a breaking change?

No

Other information: