Updated the intents extension version number

[charliescheer]

Fix

The version number on the new intents extension wasn't set correctly. This PR updates that so that the version number is the same as the main target.

Test

1. Go to the project navigator in Xcode, select the IntentsExtension -> Build Settings and filter for Version
2. Confirm that the marketing version is 2.20 and the project version is 11258

Review

(Required) Add instructions for reviewers. For example:

Only one developer and one designer are required to review these changes, but anyone can perform the review.

Release

(Required) Add a concise statement to RELEASE-NOTES.txt if the changes should be included in release notes. Include details about updating the notes in this section. For example:

RELEASE-NOTES.txt was updated in d3adb3ef with:

Added markdown support

If the changes should not be included in release notes, add a statement to this section. For example:

These changes do not require release notes.

[jleandroperez]