[FIX] l10n_pl: use correct external id

Introduced at d4d26662

closes odoo/odoo#43710

Signed-off-by: Martin Trigaux (mat) <mat@odoo.com>

addons/l10n_pl/data/res.country.state.csv

 "id","country_id:id","name","code"
-state_pl_ds,pl,"dolnośląskie","DŚ"
-state_pl_kp,pl,"kujawsko-pomorskie","KP"
-state_pl_lb,pl,"lubelskie","LB"
-state_pl_ls,pl,"lubuskie","LS"
-state_pl_ld,pl,"łódzkie","ŁD"
-state_pl_mp,pl,"małopolskie","MP"
-state_pl_mz,pl,"mazowieckie","MZ"
-state_pl_op,pl,"opolskie","OP"
-state_pl_pk,pl,"podkarpackie","PK"
-state_pl_pl,pl,"podlaskie","PL"
-state_pl_pm,pl,"pomorskie","PM"
-state_pl_sl,pl,"śląskie","ŚL"
-state_pl_sk,pl,"świętokrzyskie","ŚK"
-state_pl_wm,pl,"warmińsko-mazurskie","WM"
-state_pl_wp,pl,"wielkopolskie","WP"
-state_pl_zp,pl,"zachodniopomorskie","ZP"
+state_pl_ds,base.pl,"dolnośląskie","DŚ"
+state_pl_kp,base.pl,"kujawsko-pomorskie","KP"
+state_pl_lb,base.pl,"lubelskie","LB"
+state_pl_ls,base.pl,"lubuskie","LS"
+state_pl_ld,base.pl,"łódzkie","ŁD"
+state_pl_mp,base.pl,"małopolskie","MP"
+state_pl_mz,base.pl,"mazowieckie","MZ"
+state_pl_op,base.pl,"opolskie","OP"
+state_pl_pk,base.pl,"podkarpackie","PK"
+state_pl_pl,base.pl,"podlaskie","PL"
+state_pl_pm,base.pl,"pomorskie","PM"
+state_pl_sl,base.pl,"śląskie","ŚL"
+state_pl_sk,base.pl,"świętokrzyskie","ŚK"
+state_pl_wm,base.pl,"warmińsko-mazurskie","WM"
+state_pl_wp,base.pl,"wielkopolskie","WP"
+state_pl_zp,base.pl,"zachodniopomorskie","ZP"