CI: Bump minimum supported Rust version to 1.36.0

.appveyor.yml

       target: x86_64-pc-windows-msvc
     - channel: stable
       target: i686-pc-windows-msvc
-    - channel: 1.34.2
+    - channel: 1.36.0
       target: x86_64-pc-windows-msvc
 
 install:

.travis.yml

   - stable
   - beta
   - nightly
-  - 1.34.2
+  - 1.36.0
 script:
   - |
       cargo test --verbose;