Update iOS versioning for Cocoapods changes

[dcaunt]

Updates required for changes in IABTechLab/uid2-ios-sdk#40

Version is now specified as a tuple in code, i.e. (1, 2, 0) so I have updated the parsing and substitution. Additionally, we need to bump the version contained in UID2.podspec.json, which is in the usual . separated form.

The final piece of this is an action to publish the CocoaPod. It requires a secret token, which I've registered in this repository's Settings. These tokens expire every 5 months or so. Should we make this step a separate workflow, to run after releasing?

- name: Publish CocoaPod to trunk
env:
    COCOAPODS_TRUNK_TOKEN: ${{ secrets.COCOAPODS_TRUNK_TOKEN }}
run: |
    pod spec lint ${{ inputs.working_dir }}/UID2.podspec.json
    pod trunk push ${{ inputs.working_dir }}/UID2.podspec.json