build(nix): fix deltachat-rpc-server-source installable

Author: link2xt

flake.nix

@@ -479,8 +479,8 @@
                   pkgs.python3
                   pkgs.python3Packages.wheel
                 ];
-                buildPhase = ''python3 scripts/wheel-rpc-server.py source deltachat-rpc-server-${manifest.version}.tar.gz'';
-                installPhase = ''mkdir -p $out; cp -av deltachat-rpc-server-${manifest.version}.tar.gz $out'';
+                buildPhase = ''python3 scripts/wheel-rpc-server.py source deltachat_rpc_server-${manifest.version}.tar.gz'';
+                installPhase = ''mkdir -p $out; cp -av deltachat_rpc_server-${manifest.version}.tar.gz $out'';
               };
 
             deltachat-rpc-client =