Fix buildx warnings when creating the docker image

[dmunozv04]

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Describe the bug
Buildx now complains producing the following output:

 - StageNameCasing: Stage name 'BASE' should be lowercase (line 2)
 - FromAsCasing: 'as' and 'FROM' keywords' casing do not match (line 2)
 - FromAsCasing: 'as' and 'FROM' keywords' casing do not match (line 4)
 - StageNameCasing: Stage name 'DEP_INSTALLER' should be lowercase (line 13)
 - FromAsCasing: 'as' and 'FROM' keywords' casing do not match (line 13)

This could be fixed easily by renaming the steps

To Reproduce
Steps to reproduce the behavior:

1. Create the container image with docker buildx

Expected behavior
No warnings

Screenshots
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Additional context
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