chore(deps): update earthly/earthly docker tag to v0.8.15 (#597)

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This PR contains the following updates:

| Package | Update | Change |
|---|---|---|
| earthly/earthly | patch | `v0.8.14` -> `v0.8.15` |

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earthly.sh

@@ -1,3 +1,3 @@
 #!/bin/bash
 
-docker run --privileged -v /var/run/docker.sock:/var/run/docker.sock --rm -t -v "$(pwd):/workspace" -v earthly-tmp:/tmp/earthly:rw earthly/earthly:v0.8.14 --allow-privileged "$@"
+docker run --privileged -v /var/run/docker.sock:/var/run/docker.sock --rm -t -v "$(pwd):/workspace" -v earthly-tmp:/tmp/earthly:rw earthly/earthly:v0.8.15 --allow-privileged "$@"