fix compilation with Coq 8.6 (for some reason, that 'apply:' diverges)

program_logic/own.v

@@ -74,7 +74,7 @@ Lemma own_valid_3 γ a1 a2 a3 : own γ a1 ★ own γ a2 ★ own γ a3 ⊢ ✓ (a
 Proof. by rewrite -!own_op assoc own_valid. Qed.
 
 Lemma own_valid_r γ a : own γ a ⊢ own γ a ★ ✓ a.
-Proof. apply: uPred.always_entails_r. apply own_valid. Qed.
+Proof. apply (uPred.always_entails_r _ _). apply own_valid. Qed.
 Lemma own_valid_l γ a : own γ a ⊢ ✓ a ★ own γ a.
 Proof. by rewrite comm -own_valid_r. Qed.