mac build: use a virtualenv instead of global python packages

This helps to avoid older versions of pip-installed dependencies interfering with the build.

contrib/osx/make_osx

@@ -73,8 +73,15 @@ PYTHON_CONFIGURE_OPTS="--enable-framework" pyenv install -s $PYTHON_VERSION && \
 pyenv global $PYTHON_VERSION || \
 fail "Unable to use Python $PYTHON_VERSION"
 
+# create a fresh virtualenv
+# This helps to avoid older versions of pip-installed dependencies interfering with the build.
+VENV_DIR="$CONTRIB_OSX/build-venv"
+rm -rf "$VENV_DIR"
+python3 -m venv $VENV_DIR
+source $VENV_DIR/bin/activate
+
 info "Installing build dependencies"
-python3 -m pip install --no-dependencies -Ir ./contrib/deterministic-build/requirements-build-mac.txt --user \
+python3 -m pip install --no-dependencies --no-warn-script-location -Ir ./contrib/deterministic-build/requirements-build-mac.txt \
     || fail "Could not install build dependencies"
 
 info "Using these versions for building $PACKAGE:"
@@ -128,19 +135,19 @@ DoCodeSignMaybe "CalinsQRReader.app" "${d}/build/Release/CalinsQRReader.app"
 
 
 info "Installing requirements..."
-python3 -m pip install --no-dependencies -Ir ./contrib/deterministic-build/requirements.txt --user \
+python3 -m pip install --no-dependencies --no-warn-script-location -Ir ./contrib/deterministic-build/requirements.txt \
     || fail "Could not install requirements"
 
 info "Installing hardware wallet requirements..."
-python3 -m pip install --no-dependencies -Ir ./contrib/deterministic-build/requirements-hw.txt --user \
+python3 -m pip install --no-dependencies --no-warn-script-location -Ir ./contrib/deterministic-build/requirements-hw.txt \
     || fail "Could not install hardware wallet requirements"
 
 info "Installing dependencies specific to binaries..."
-python3 -m pip install --no-dependencies -Ir ./contrib/deterministic-build/requirements-binaries-mac.txt --user \
+python3 -m pip install --no-dependencies --no-warn-script-location -Ir ./contrib/deterministic-build/requirements-binaries-mac.txt \
     || fail "Could not install dependencies specific to binaries"
 
 info "Building $PACKAGE..."
-python3 -m pip install --no-dependencies --user . > /dev/null || fail "Could not build $PACKAGE"
+python3 -m pip install --no-dependencies --no-warn-script-location . > /dev/null || fail "Could not build $PACKAGE"
 
 info "Faking timestamps..."
 for d in ~/Library/Python/ ~/.pyenv .; do