CI: move 2.7_SLOW -> 3.6_SLOW (pandas-dev#20559)

Author: jreback

.travis.yml

@@ -56,7 +56,7 @@ matrix:
     # In allow_failures
     - dist: trusty
       env:
-        - JOB="2.7_SLOW" SLOW=true
+        - JOB="3.6_SLOW" SLOW=true
     # In allow_failures
     - dist: trusty
       env:
@@ -72,7 +72,7 @@ matrix:
     allow_failures:
       - dist: trusty
         env:
-          - JOB="2.7_SLOW" SLOW=true
+          - JOB="3.6_SLOW" SLOW=true
       - dist: trusty
         env:
           - JOB="3.6_NUMPY_DEV" TEST_ARGS="--skip-slow --skip-network" PANDAS_TESTING_MODE="deprecate"

ci/requirements-2.7_SLOW.build renamed to ci/requirements-3.6_SLOW.build

@@ -1,5 +1,5 @@
-python=2.7*
+python=3.6*
 python-dateutil
 pytz
-numpy=1.10*
+numpy
 cython

ci/requirements-2.7_SLOW.pip renamed to ci/requirements-3.6_SLOW.pip

@@ -1,7 +1,7 @@
 python-dateutil
 pytz
-numpy=1.10*
-matplotlib=1.4.3
+numpy
+matplotlib
 scipy
 patsy
 xlwt