add source usage tracking evergreen issue

[sndrs]

What are you changing?

• adds code to keep @guardian/source-* installations #1058 up to date

Why?

• we want to know where source is being used and which versions, in the most lightweight way possible

N.B. i think this needs to go to main before the action will be available to run

[changeset-bot]

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Latest commit: 94fd47b

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