Bump minimum required runtime version to 0.11

0.11 will definitely include some changes that require an updated
runtime - for example
kaitai-io/kaitai_struct_cpp_stl_runtime#67 or
the fact that (once the `serialization` branch is merged) the compiler
will no longer insert `align_to_byte()` calls and will instead rely on
the runtime libraries to do it:
kaitai-io/kaitai_struct#1070 (comment)).

Besides, we need to require something newer than 0.9 to fix the version
check in Python:
kaitai-io/kaitai_struct#804 (comment)

shared/src/main/scala/io/kaitai/struct/format/KSVersion.scala

@@ -91,5 +91,5 @@ object KSVersion {
     * language supports it) when trying to use generated file together
     * with this older runtime API.
     */
-  val minimalRuntime: KSVersion = KSVersion.fromStr("0.9")
+  val minimalRuntime: KSVersion = KSVersion.fromStr("0.11")
 }