Convert to TF 0.12/0.13. Update to context.tf. Update GitHub Actions. Use `go` modules @aknysh (#40) what Convert to TF 0.12/0.13 Update to context.tf Update GitHub Actions Use go modules why Keep up to date Standardization related Closes #23 Closes #25 Closes #27 Closes #29 Closes #31 Closes #34 Closes #37 Closes #38 Closes #21 Closes #26 Closes #28 Closes #30 Closes #33