Deprecating inspecting. (#4009)

A [code search on
github](https://github.com/search?q=import+io.kotest.assertions.inspecting+NOT+is:fork&type=code)
shows no usages aside from Kotest itself, albeit being in Kotest since
2018.

Kotlin provides the `with` scoping function which does basically the
same thing.

Kotest also provides `assertSoftly` on an object which adds it to scope
and executes all assertions before failing.

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Co-authored-by: Sam <sam@sksamuel.com>

kotest-assertions/kotest-assertions-shared/src/commonMain/kotlin/io/kotest/assertions/inspecting.kt

@@ -29,6 +29,7 @@ package io.kotest.assertions
  * @param inspector the inspector in which further assertions and inspections can be done
  * @author Hannes Thaller
  */
+@Deprecated(message = "Use with(obj) or assertSofty(obj) instead. Deprecated in 5.9. Will be removed in 6.0")
 fun <K> inspecting(obj: K, inspector: K.() -> Unit) {
     obj.inspector()
 }