Publish latest tag for Docker image

[felixbarny]

closes #2621

Adapted from @AlexanderWert's work in elastic/apm-aws-lambda#199 and elastic/apm-agent-nodejs#2742

[AlexanderWert]

LGTM

[ghost]

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• Start Time: 2022-06-01T08:00:39.905+0000

• Duration: 49 min 35 sec

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Test	Results
Failed	0
Passed	2904
Skipped	22
Total	2926

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