list all licenses used in the rust dependencies

recipe/meta.yaml

@@ -12,6 +12,16 @@ build:
   number: 1
   skip: True  # [py<36]
   script:
+    # Install cargo-license
+    - export CARGO_HOME="$BUILD_PREFIX/cargo"
+    - mkdir $CARGO_HOME
+    - cargo install cargo-license
+    - 
+    # Check that all downstream libraries licenses are present
+    - export PATH=$PATH:$CARGO_HOME/bin
+    - cargo-license --json > dependencies.json
+    - cat dependencies.json
+
     - export PYO3_CROSS_INCLUDE_DIR=$PREFIX/include    # [build_platform != target_platform]
     - export PYO3_CROSS_LIB_DIR=$PREFIX/lib            # [build_platform != target_platform]
     - {{ PYTHON }} -m pip install . -vv
@@ -65,7 +75,7 @@ test:
 
 about:
   home: https://github.com/pyca/cryptography
-  license: Apache-2.0 AND BSD-3-Clause AND PSF-2.0
+  license: Apache-2.0 AND BSD-3-Clause AND PSF-2.0 AND MIT
   license_family: BSD
   license_file: LICENSE
   summary: Provides cryptographic recipes and primitives to Python developers