Elixir 1.15

[mnishiguchi]

Description

Support Elixir 1.15 / OTP 26 See https://github.com/nerves-project/nerves/issues/873

Changes

• ci: remove coveralls to fix ssl_verify_fun issue
• ci: update versions in config.yml
• chore: use charlist sigil in test
  • let each version of Elixir print charlists the way it prefers
• chore: make credo happy
  • alias order
  • max line length
  • ~S when "" appears in text
  • disable check for necessary apply call
• chore: deprecated Logger.warn to Logger.warning

Notes

• many files are changed but most changes are for credo checks and deprecation fixes

[fhunleth]

Looks good! Thanks for fixing so many of these chore tasks.