build(package): bump up typescript@4.3

[kwonoj]

Description:

Looks like tsc gets bit more strict for tuple types. Those 2 are marked as deprecated but instead of trying to change public surfaces bene internals to workaround.

BREAKING CHANGE:

Related issue (if exists):

[kwonoj]

CI fails with api_gurdian probably due to 4.3 changes

-export declare const observable: string | symbol;
+export declare const observable: string | typeof Symbol.observable;

This seems bit.. concerning? Curious if we'll hit some regression by this.

[cartant]

I don't think we should bump TS without some changes to CI to ensure that at least the tests (the dtslint tests especially) are run using our minimum-supported version of 4.2. In fact, given that that's our minimum, I'm not sure we should bump at all. IIRC, we did not do this for v6.

The code fixes in this LGTM. I'd prefer them to be separated from the bumping.

Also, I think we should always use a tildle version range with TS as it does not follow semver and minors can be breaking.

[kwonoj]

ah that's good point.

[benlesh]

@cartant @kwonoj I've reverted the change to the package.json, so we're only using 4.2 for the project. I think it's fine to temporarily, locally update, but we need to support 4.2 for the duration of version 7.

We can discuss updating and leveraging tests to ensure 4.2 support another time. Right now we just need to fix CI.