dev-python/cryptography: re-add a BDEPEND on rust

During the migration to slotted rust, an explicit dependency on
virtual/rust was entirely dropped. But cryptography must explicitly
depend on rust, because it defines CARGO_OPTIONAL (in order to get
access to cargo setup functions without also exporting cargo phase
functions, as we want the distutils-r1 phase functions instead).

No revbump as users who successfully built it will not need the bdep
fix.

Fixes: 01ba4dc619
Signed-off-by: Eli Schwartz <eschwartz@gentoo.org>

dev-python/cryptography/cryptography-43.0.3-r1.ebuild

@@ -79,6 +79,7 @@ DEPEND="
 "
 
 BDEPEND="
+	${RUST_DEPEND}
 	dev-python/setuptools[${PYTHON_USEDEP}]
 	test? (
 		dev-python/certifi[${PYTHON_USEDEP}]