[PPSIG] Add meeting agenda in ppsigs

[KevinLi43]

No description provided.

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✅ KevinLi43
❌ lihaoxuan04

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[onecatcn]

LGTM

[shiyutang]

可以根据上述修改，并进一步补充参与人的list

[shiyutang]

两处细节～

[shiyutang]

ppsigs/meetings/2023/2023-07-04-meeting-agenda.md需要修改成0705，另外minutes可以不用增加，我已经增加并合入了～

[shiyutang]

LGTM