nftables: Conditionally add ${PN}-python as RDEPENDS for ptest

This commit updates the RDEPENDS for the ptest package to include
${PN}-python only when the 'python' PACKAGECONFIG option is enabled.

This change will ensure that we dont get below failure when ptest is enabled in the distro features,
and packageconfig is not set.
It causes this error-
ERROR: Nothing RPROVIDES 'nftables-python' (meta-openembedded/meta-networking/recipes-filter/nftables/nftables_1.1.6.bb RDEPENDS on or otherwise requires it)
NOTE: Runtime target 'nftables-python' is unbuildable, removing...
Missing or unbuildable dependency chain was: ['nftables-python']
ERROR: Required build target 'nftables' has no buildable providers.
Missing or unbuildable dependency chain was: ['nftables', 'nftables-python']

Signed-off-by: Naman Jain <namanj1@kpit.com>
Signed-off-by: Khem Raj <khem.raj@oss.qualcomm.com>

Author: Naman Jain

meta-networking/recipes-filter/nftables/nftables_1.1.6.bb

@@ -72,7 +72,10 @@ do_install() {
     fi
 }
 
-RDEPENDS:${PN}-ptest += " ${PN}-python bash coreutils make iproute2 iputils-ping procps python3-core python3-ctypes python3-json python3-misc sed util-linux"
+RDEPENDS:${PN}-ptest += " \
+	bash coreutils make iproute2 iputils-ping procps python3-core python3-ctypes python3-json python3-misc sed util-linux \
+	${@bb.utils.contains('PACKAGECONFIG', 'python', '${PN}-python', '', d)} \
+"
 
 
 # For ptests compile the kernel with CONFIG_NFT_TPROXY