Update for new requirements

Author: isuruf

appveyor.yml

@@ -33,7 +33,7 @@ environment:
     - BUILD_TYPE: "Release"
       COMPILER: MSVC15
       PLATFORM: "Win32"
-      PYTHON_VERSION: 37
+      PYTHON_VERSION: 39
       CONDA_INSTALL_LOCN: C:\\Miniconda36
       WITH_MPFR: yes
       WITH_MPC: yes
@@ -61,7 +61,7 @@ install:
 - if [%COMPILER%]==[MSVC15] echo %PATH%
 - if [%COMPILER%]==[MSVC15] if [%WITH_MPFR%]==[yes] conda install --yes mpfr=3.1.5
 - if [%COMPILER%]==[MSVC15] if [%WITH_MPC%]==[yes] conda install --yes mpc=1.0.3
-- if [%COMPILER%]==[MSVC15] if [%WITH_LLVM%]==[yes] conda install --yes llvmdev=3.9
+- if [%COMPILER%]==[MSVC15] if [%WITH_LLVM%]==[yes] conda install --yes llvmdev=4.0
 
 - if [%COMPILER%]==[MinGW] set "PATH=C:\MinGW\bin;%PATH%"
 - if [%COMPILER%]==[MinGW] mingw-get update