message: Update pybind11 tag
diff: @@ -8,7 +8,7 @@ readonly name="pybind11"
  readonly ownership="PyBind11 Upstream <robot@adios2>"
  readonly subtree="thirdparty/pybind11/pybind11"
  readonly repo="https://github.com/pybind/pybind11.git"
  -readonly tag="v2.1.1"
  +readonly tag="v2.2.1"
  readonly shortlog="true"
  readonly paths="
  "
  