chore: add a nix flake check for the devShell

Author: yvan-sraka

flake.nix

@@ -1381,6 +1381,9 @@
           psql_17 = makeCheckHarness basePackages.psql_17.bin;
           psql_orioledb-17 = makeCheckHarness basePackages.psql_orioledb-17.bin;
           inherit (basePackages) wal-g-2 wal-g-3 dbmate-tool pg_regress;
+          devShell = pkgs.runCommand "check-devShell" { buildInputs = [ devShells.default ]; } ''
+            touch $out
+          '';
         } // pkgs.lib.optionalAttrs (system == "aarch64-linux") {
           inherit (basePackages) postgresql_15_debug postgresql_15_src postgresql_orioledb-17_debug postgresql_orioledb-17_src postgresql_17_debug postgresql_17_src;
         };