install latest pip, add setuptools_scm to BUILD_DEPENDS (#62)

* install latest pip, add setuptools_scm to BUILD_DEPENDS

* remove comments

* pre-install setuptools_scm only for mac 3.5 build

Author: robbuckley

.travis.yml

@@ -51,6 +51,9 @@ matrix:
       env:
         - MB_PYTHON_VERSION=3.5
         - MB_PYTHON_OSX_VER=10.6 # no python.org 10.9 builds for 3.5
+        # WAR for setup_requires TLS issue with Python 3.5 on macOS
+        # see https://github.com/pandas-dev/pandas/issues/28954 
+        - EXTRA_BUILD_DEP="setuptools_scm"
     - os: osx
       language: generic
       env:
@@ -68,7 +71,7 @@ before_install:
     - python -c "import fcntl; fcntl.fcntl(1, fcntl.F_SETFL, 0)"
     - CONTAINER="wheels";  # pre-relesae
     - BUILD_COMMIT=$BUILD_COMMIT;
-    - BUILD_DEPENDS="$NP_BUILD_DEP Cython==0.28.2"
+    - BUILD_DEPENDS="$NP_BUILD_DEP $EXTRA_BUILD_DEP Cython==0.28.2"
       # binary-only for cryptogrpahy. See https://github.com/pandas-dev/pandas/issues/26589
       # Moto picks it up, and they don't distribute 32-bit wheels.
     - TEST_DEPENDS="$NP_TEST_DEP pytest>=4.0.2 pytest-xdist pytest-mock moto hypothesis>=3.58 wheel==0.31.1 cryptography --only-binary=cryptography"