seafile-client: build v8.0.7 from proper commit

Follow-up to #170730
After release, the v8.0.7 tag had been re-tagged to a newer but broken state.
This commit does not change the built program but only ensures that it continues
to be buildable.

pkgs/applications/networking/seafile-client/default.nix

···
   src = fetchFromGitHub {
     owner = "haiwen";
     repo = "seafile-client";
-    rev = "v${version}";
+    # Tag v8.0.7 used to point to this commit, but was re-tagged later to a state
+    # that fails to link properly
+    rev = "8b96abf64e6aa19e3beeff6b322bcd6d28120bdd";
     sha256 = "00wfr7dvbyl7pg1xgssgz8a94c7c4n5r9266lhy9qcbz456hdcgj";
   };