subnet deployment generator v0.1.5

What's Changed

• Update xdc-attach.sh by @AnilChinchawale in #89
• improve testnet script and use old way for backward compatible by @liam-lai in #90
• update script for env variable name by @liam-lai in #92
• Generator macsupport by @wanwiset25 in #91

Full Changelog: v0.1.4...v0.1.5