DEPS: drop 3.6 (pandas-dev#34472)

Author: fangchenli

ci/deps/azure-37-minimum_versions.yaml

@@ -2,7 +2,7 @@ name: pandas-dev
 channels:
   - conda-forge
 dependencies:
-  - python=3.6.1
+  - python=3.7.1
 
   # tools
   - cython=0.29.16
@@ -14,7 +14,7 @@ dependencies:
 
   # pandas dependencies
   - beautifulsoup4=4.6.0
-  - bottleneck=1.3.1
+  - bottleneck=1.2.1
   - jinja2=2.8
   - numba=0.46.0
   - numexpr=2.6.2