pin python cryptography to 3.2.1

This is the last version of python cryptography that will cleanly
build on Ubuntu Touch 16.04. The 3.3 series depends on newer openssl and
the 3.4 series depends on Rust.

dev-build.sh

@@ -79,6 +79,9 @@ export LD_LIBRARY_PATH
 echo "Installing PyInstaller..."
 ${PYTHON} -m pip install --upgrade pyinstaller
 
+echo "Installing cryptography 3.2.1"
+${PYTHON} -m pip install cryptography==3.2.1
+
 echo "Installing Pantalaimon..."
 CFLAGS=-I"${OLM_DIR}/usr/local/include -I${OLM_DIR}/usr/local/include" LDFLAGS="-L${OLM_DIR}/usr/local/lib" ${PYTHON} -m pip install --upgrade pantalaimon