feat: add Pawn rule and textual fix to Pawn specifications

chess/src/main/scala/io/github/chess/model/rules/pawn/PawnRule.scala

@@ -0,0 +1,18 @@
+/*
+ * MIT License
+ * Copyright (c) 2023 Cesario Jahrim Gabriele & Derevyanchenko Maxim & Felice Mirko & Kentpayeva Madina
+ *
+ * Full license description available at: https://github.com/jahrim/PPS-22-chess/blob/master/LICENSE
+ */
+package io.github.chess.model.rules.pawn
+
+import io.github.chess.model.{Move, Position}
+import io.github.chess.model.rules.ChessRule
+import io.github.chess.model.Pawn
+
+/** Implementation of the [[ChessRule]] that applies the rules of the [[Pawn]]. */
+case class PawnRule() extends ChessRule:
+
+  override def findMoves(position: Position): Set[Move] =
+    ForwardOneRule().findMoves(position) ++
+      DoubleMoveRule().findMoves(position)

chess/src/test/scala/io/github/chess/model/rules/pawn/PawnRulesSpec.scala

@@ -24,8 +24,8 @@ class PawnRulesSpec extends AbstractSpec:
     all(moves) should have(Symbol("to")(pawnNextPosition))
   }
 
-  "Double move rule" should """let move the pawn only to the rank two steps ahead of the pawn's current position, "
-    without changing its file""" in {
+  "Double move rule" should "let move the pawn only to the rank two steps ahead of the pawn's current position, " +
+    "without changing its file" in {
     val moves = doubleStepRule.findMoves(pawnInitialPosition)
     moves should have size 1
     all(moves) should have(Symbol("to")(pawnDoubleStepPosition))