Minimum rust version increased to 1.33

This is because the updated rand_core crate to 0.6 uses getrandom
at version 0.2 which uses the cfg_target_vendor feature which
was stabilized at 1.33: rust-lang/rust#57465

Author: PaulGrandperrin

.travis.yml

@@ -2,7 +2,7 @@ language: rust
 sudo: false
 dist: trusty
 rust:
-- 1.32.0
+- 1.33.0
 - stable
 - beta
 - nightly

appveyor.yml

@@ -4,7 +4,7 @@ environment:
   - TARGET: nightly-i686-pc-windows-msvc
   - TARGET: nightly-x86_64-pc-windows-gnu
   - TARGET: nightly-i686-pc-windows-gnu
-  - TARGET: 1.32.0-x86_64-pc-windows-gnu
+  - TARGET: 1.33.0-x86_64-pc-windows-gnu
 install:
   - ps: Start-FileDownload "https://static.rust-lang.org/dist/rust-${env:TARGET}.exe" -FileName "rust-install.exe"
   - ps: .\rust-install.exe /VERYSILENT /NORESTART /DIR="C:\rust" | Out-Null