nix(refactor): Move shell scripts to subdirectory nix/tools

nix/tools/release/default.nix

@@ -44,7 +44,7 @@ let
             --replace nightly \
             "postgrest-nightly-$suffix-linux-x64-static.tar.xz"
         else
-          changes="$(sed -n "1,/$_arg_version/d;/## \[/q;p" ${../../CHANGELOG.md})"
+          changes="$(sed -n "1,/$_arg_version/d;/## \[/q;p" ${../../../CHANGELOG.md})"
 
           tar cvJf "postgrest-$_arg_version-linux-x64-static.tar.xz" \
             -C ${postgrest}/bin postgrest

nix/tools/withtools.nix

@@ -27,7 +27,7 @@ let
         if test ! -v PGRST_DB_URI; then
           export PATH=${postgresql}/bin:"$PATH"
 
-          exec ${../test/with_tmp_db} "$_arg_command" "''${_arg_leftovers[@]}"
+          exec ${../../test/with_tmp_db} "$_arg_command" "''${_arg_leftovers[@]}"
         else
           "$@"
         fi