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

Fixed in #23769. Closes #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