v1.15.6

What's Changed

• fix: add legacy skyway message by @maharifu in #1234
• fix: sort validators with same score by address by @maharifu in #1235
• feat: add node sale contract details in paloma by @maharifu in #1236
• chore: add optional BUILD_TAGS to Makefile by @maharifu in #1237
• chore: Fix testnet node address in readme by @verabehr in #1239
• feat: record pigeon version on valset by @maharifu in #1240
• chore: update README to v1.15.6 by @maharifu in #1242

Full Changelog: v1.15.5...v1.15.6