update epp dependency

[JeanMertz]

Closes https://github.com/blendle/kubecrt/issues/7. See https://github.com/blendle/epp/releases/tag/v2.0.0-rc2

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• add required template helper

  This equals the templating function used in Helm.

  It provides a way to "require" a specific value to exist, or otherwise exit the execution of the template parsing.

  This can be useful when expecting an environment variable, and not accepting an empty string as value.

  Example:

  password: {{ required "we really need this!" (env "SECRET_PASSWORD") }}

• add include template helper

  This equals the templating function used in Helm.

  It provides the same functionality as the Golang built-in "template" function, but returns the produced template string as the return value, allowing you to pipe the value to another template function.

  example:

  {{ define "foobar" }}
  foo:
  bar: baz
  {{ end }}
  
  qux:
  {{ include "foobar" . | indent 2 }}
  
  # qux:
  #   foo:
  #     bar: baz