python3-pybind11: Remove the Boost dependency

Boost is an optional dependency and it is only used in tests which are
disabled by default in this recipe.

References:
https://github.com/pybind/pybind11/blob/master/tests/CMakeLists.txt#L325

Moreover, the Boost is an enormously large and complex suite of utility
libraries that cost the filesystem memory footprint of Embedded devices.

Signed-off-by: Pratik Manvar <pratik.manvar@ifm.com>

meta-python/recipes-devtools/python/python3-pybind11_2.8.1.bb

@@ -3,8 +3,6 @@ HOMEPAGE = "https://github.com/wjakob/pybind11"
 LICENSE = "BSD-2-Clause"
 LIC_FILES_CHKSUM = "file://LICENSE;md5=774f65abd8a7fe3124be2cdf766cd06f"
 
-DEPENDS = "boost"
-
 SRC_URI = "git://github.com/pybind/pybind11.git;branch=master;protocol=https \
            file://0001-Do-not-strip-binaries.patch \
            file://0001-Do-not-check-pointer-size-when-cross-compiling.patch \