python3-pystache: remove, unmaintained

Pystache hasn't been maintained since 2014.  One maintained alternative
is https://github.com/noahmorrison/chevron.

Signed-off-by: Ross Burton <ross.burton@arm.com>
Signed-off-by: Khem Raj <raj.khem@gmail.com>
Signed-off-by: Trevor Gamblin <trevor.gamblin@windriver.com>

meta-python/recipes-core/packagegroups/packagegroup-meta-python.bb

@@ -346,7 +346,6 @@ RDEPENDS:packagegroup-meta-python3 = "\
     python3-pyserial \
     python3-pysocks \
     python3-pysonos \
-    python3-pystache \
     python3-pystemd \
     python3-pytest-asyncio \
     python3-pytest-benchmark \