added string to language type

[ZenMasterJacob20011]

https://formio.atlassian.net/browse/FIO-10134

Link to Jira Ticket

N/A

Description

What changed?

Added string to language type

Why have you chosen this solution?

We have a typeof check for language to be type of string. Seems like we missed adding the type def of string to language

Breaking Changes / Backwards Compatibility

N/A

Dependencies

N/A

How has this PR been tested?

N/A

Checklist:

• I have completed the above PR template
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation (if applicable)
• My changes generate no new warnings
• My changes include tests that prove my fix is effective (or that my feature works as intended)
• New and existing unit/integration tests pass locally with my changes
• Any dependent changes have corresponding PRs that are listed above