Fix removeCategory method in Beer class

Related to #13

---

For more details, open the [Copilot Workspace session](https://copilot-workspace.githubnext.com/springframeworkguru/spring-6-rest-mvc/issues/13?shareId=XXXX-XXXX-XXXX-XXXX).

.devcontainer/devcontainer.json

@@ -0,0 +1,7 @@
+{
+  "tasks": {
+    "test": "./mvnw test",
+    "build": "./mvnw clean verify",
+    "launch": "mvn spring-boot:run"
+  }
+}

src/main/java/guru/springframework/spring6restmvc/entities/Beer.java

@@ -0,0 +1,53 @@
+package guru.springframework.spring6restmvc.entities;
+
+import lombok.*;
+import org.hibernate.annotations.CreationTimestamp;
+import org.hibernate.annotations.UpdateTimestamp;
+
+import jakarta.persistence.*;
+import java.math.BigDecimal;
+import java.time.LocalDateTime;
+import java.util.HashSet;
+import java.util.Set;
+import java.util.UUID;
+
+@Getter
+@Setter
+@Builder
+@NoArgsConstructor
+@AllArgsConstructor
+@Entity
+public class Beer {
+
+    @Id
+    @GeneratedValue(strategy = GenerationType.AUTO)
+    private UUID id;
+
+    private String name;
+    private String style;
+    private String upc;
+    private Integer quantityOnHand;
+    private BigDecimal price;
+
+    @CreationTimestamp
+    private LocalDateTime createdDate;
+
+    @UpdateTimestamp
+    private LocalDateTime lastModifiedDate;
+
+    @ManyToMany
+    @JoinTable(name = "beer_category",
+            joinColumns = @JoinColumn(name = "beer_id"),
+            inverseJoinColumns = @JoinColumn(name = "category_id"))
+    private Set<Category> categories = new HashSet<>();
+
+    public void addCategory(Category category){
+        this.categories.add(category);
+        category.getBeers().add(this);
+    }
+
+    public void removeCategory(Category category){
+        this.categories.remove(category);
+        category.getBeers().remove(this);
+    }
+}