21.0

What's Changed

This is the set of changes for protocol 21.

Generated summary:

• Add Soroban write fee to LCM. by @dmkozh in #173
• Add detailed Soroban resource fee info in txmeta by @dmkozh in #175
• Sync next to curr for p21 by @graydon in #180
• (curr) Add contract spec for Hash by @jayz22 in #182

Full Changelog: v20.1...v21.0