chore: add regression test for scala#23225 (scala#24451)

Fixed in scala#23769. Closes scala#23225.

Author: hamzaremmal

tests/pos/i23225.scala

@@ -0,0 +1,16 @@
+import language.experimental.captureChecking
+
+class A
+
+def run(f: PartialFunction[A, A]^): A = f(A())
+
+class File extends caps.SharedCapability:
+  def read() = ()
+
+def main() =
+  val file = File()
+
+  run:
+    case a =>
+      file.read()
+      a