set paths.lockfile for pip example...

even with the new default, it's good to be explicit.
And the examples will still refer to the main branch while running ci
checks for this

examples/packages/languages/python-local-development-multiple-packages/default.nix

@@ -32,6 +32,7 @@ in {
     "subpkg2"
   ];
 
+  paths.lockFile = "lock.${config.deps.stdenv.system}.json";
   pip = {
     requirementsList = [
       "${config.paths.package}/subpkg1"

examples/packages/languages/python-local-development/default.nix

@@ -36,6 +36,7 @@ in {
     ];
   };
 
+  paths.lockFile = "lock.${config.deps.stdenv.system}.json";
   pip = {
     # Setting editables.$pkg.null will link the current project root as an editable
     # for the root package (my-tool here), or otherwise copy the contents of mkDerivation.src

examples/packages/languages/python-packaging-ansible/default.nix

@@ -21,6 +21,7 @@
     ];
   };
 
+  paths.lockFile = "lock.${config.deps.stdenv.system}.json";
   pip = {
     requirementsList = ["${config.name}==${config.version}"];
   };

examples/packages/languages/python-packaging-apache-airflow/default.nix

@@ -43,6 +43,7 @@ in {
     ];
   };
 
+  paths.lockFile = "lock.${config.deps.stdenv.system}.json";
   pip = {
     requirementsList = [
       "apache-airflow"

examples/packages/languages/python-packaging-odoo/default.nix

@@ -32,6 +32,7 @@ in {
     inherit src;
   };
 
+  paths.lockFile = "lock.${config.deps.stdenv.system}.json";
   pip = {
     requirementsList = [
       "${src}"

examples/packages/languages/python-packaging-pillow/default.nix

@@ -39,6 +39,7 @@
     ];
   };
 
+  paths.lockFile = "lock.${config.deps.stdenv.system}.json";
   pip = {
     requirementsList = ["${config.name}==${config.version}"];
     pipFlags = [