* debian: fix up postinst bad substitution
Fix up postinst bad substitution caused by Bash string manipulation in the Dash script.
* debian: update compat file
Fix up the warning caused by compatibility levels before 10 are deprecated.
* debian: replace user nobody in systemd file with dynamicuser
* debian: remove dependency on apg and pwgen in control file
* debian: update shadowsocks-rust-server@.service
Add `DynamicUser=yes` in shadowsocks-rust-server@.service
* debian: update shadowsocks-rust-local@.service
Add `DynamicUser=yes` in shadowsocks-rust-local@.service
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Co-authored-by: mesher2024 <mesher2024@users.noreply.github.com>