dev-python/standardwebhooks: fix deprecated build backend

Closes: https://bugs.gentoo.org/979160
Signed-off-by: Florian Albrechtskirchinger <falbrechtskirchinger@gmail.com>

dev-python/standardwebhooks/standardwebhooks-1.0.1.ebuild

@@ -21,3 +21,11 @@ KEYWORDS="~amd64 ~arm64"
 
 EPYTEST_PLUGINS=()
 distutils_enable_tests pytest
+
+src_prepare() {
+	distutils-r1_src_prepare
+
+	# fix build backend
+	# https://bugs.gentoo.org/979160
+	sed -i "/^build-backend = /s/:__legacy__//" pyproject.toml || die
+}