Release 2.3.2

What's Changed

• Update doc 2.3 [skip ci] by @YuanTingHsieh in #1840
• Add garbage collection at the end of each round in cyclic controller by @IsaacYangSLA in #1860
• Add client heartbeat log by @YuanTingHsieh in #1864
• [2.3 branch] remove wget in df_stats example by @chesterxgchen in #1879
• Support Roche requirements and fixes by @yanchengnv in #1868

Full Changelog: 2.3.1...2.3.2