don't use pip cache when installing brand new version (#128)

Author: graebm

continuous-delivery/test_prod_pypi.yml

@@ -20,7 +20,7 @@ phases:
       - cd aws-iot-device-sdk-python-v2
       - CURRENT_TAG_VERSION=$(git describe --tags | cut -f2 -dv)
       - python3 continuous-delivery/wait-for-pypi.py awsiotsdk $CURRENT_TAG_VERSION --index https://pypi.python.org/pypi
-      - python3 -m pip install --user awsiotsdk==$CURRENT_TAG_VERSION
+      - python3 -m pip install --no-cache-dir --user awsiotsdk==$CURRENT_TAG_VERSION
       - python3 samples/basic_discovery.py --region us-east-1 --cert /tmp/certificate.pem --key /tmp/privatekey.pem --root-ca /tmp/AmazonRootCA1.pem --thing-name aws-sdk-crt-unit-test --print-discover-resp-only -v Trace
 
   post_build:

continuous-delivery/test_test_pypi.yml

@@ -22,7 +22,7 @@ phases:
       # this is here because typing isn't in testpypi, so pull it from prod instead
       - python3 -m pip install typing
       - python3 continuous-delivery/wait-for-pypi.py awsiotsdk $CURRENT_TAG_VERSION --index https://test.pypi.org/pypi
-      - python3 -m pip install -i https://testpypi.python.org/simple --user awsiotsdk==$CURRENT_TAG_VERSION
+      - python3 -m pip install --no-cache-dir -i https://testpypi.python.org/simple --user awsiotsdk==$CURRENT_TAG_VERSION
       - python3 samples/basic_discovery.py --region us-east-1 --cert /tmp/certificate.pem --key /tmp/privatekey.pem --root-ca /tmp/AmazonRootCA1.pem --thing-name aws-sdk-crt-unit-test --print-discover-resp-only -v Trace
 
   post_build: