Discounts REST API: update IsInCategory typing (#2908)

* `DiscountCondition\IsInCategory`: Use integers instead of strings

Author: adriendupuis

docs/api/rest_api/rest_api_reference/input/examples/discounts/POST/DiscountCreate.json.example

@@ -22,7 +22,7 @@
         "conditions": [
             {
                 "class": "Ibexa\\Discounts\\Value\\DiscountCondition\\IsInCategory",
-                "parameters": [["1", "2"]]
+                "parameters": [[1, 2]]
             }
         ]
     }

docs/api/rest_api/rest_api_reference/input/examples/discounts/identifier/PATCH/DiscountUpdate.json.example

@@ -4,7 +4,7 @@
         "conditions": [
             {
                 "class": "Ibexa\\Discounts\\Value\\DiscountCondition\\IsInCategory",
-                "parameters": [["1", "3"]]
+                "parameters": [[1, 3]]
             }
         ]
     }

docs/api/rest_api/rest_api_reference/rest_api_reference.html

@@ -150650,7 +150650,7 @@ <h6 class="heading text-gray border-bottom pb-2">Types</h6>
         &quot;conditions&quot;: [
             {
                 &quot;class&quot;: &quot;Ibexa\\Discounts\\Value\\DiscountCondition\\IsInCategory&quot;,
-                &quot;parameters&quot;: [[&quot;1&quot;, &quot;2&quot;]]
+                &quot;parameters&quot;: [[1, 2]]
             }
         ]
     }
@@ -150736,7 +150736,7 @@ <h6 class="heading text-gray border-bottom pb-2">Types</h6>
         &quot;conditions&quot;: [
             {
                 &quot;class&quot;: &quot;Ibexa\\Discounts\\Value\\DiscountCondition\\IsInCategory&quot;,
-                &quot;parameters&quot;: [[&quot;1&quot;, &quot;2&quot;]]
+                &quot;parameters&quot;: [[1, 2]]
             }
         ]
     }
@@ -151799,7 +151799,7 @@ <h6 class="heading text-gray border-bottom pb-2">Types</h6>
         &quot;conditions&quot;: [
             {
                 &quot;class&quot;: &quot;Ibexa\\Discounts\\Value\\DiscountCondition\\IsInCategory&quot;,
-                &quot;parameters&quot;: [[&quot;1&quot;, &quot;3&quot;]]
+                &quot;parameters&quot;: [[1, 3]]
             }
         ]
     }
@@ -151867,7 +151867,7 @@ <h6 class="heading text-gray border-bottom pb-2">Types</h6>
         &quot;conditions&quot;: [
             {
                 &quot;class&quot;: &quot;Ibexa\\Discounts\\Value\\DiscountCondition\\IsInCategory&quot;,
-                &quot;parameters&quot;: [[&quot;1&quot;, &quot;3&quot;]]
+                &quot;parameters&quot;: [[1, 3]]
             }
         ]
     }