Cargo.toml: lto = "thin"

Refer to <nabijaczleweli/systemd-zram-generator.deb@8f2f3fa>,
building package on Debian 10+ and Ubuntu 20.04+ will fail with `lto = true`.

Moreover, tested with
<https://build.opensuse.org/package/show/home:alvistack:systemd/zram-generator>,
`lto = "thin"` working well for all support OS, including
CentOS/Fedora/Debian/Ubuntu/openSUSE.

Signed-off-by: Wong Hoi Sing Edison <[email protected]>

Author: hswong3i

Cargo.toml

@@ -23,4 +23,4 @@ tempfile = "3"
 fs_extra = "1.1"
 
 [profile.release]
-lto = true
+lto = "thin"