Exclude appveyor pandas version

Author: dstansby

.appveyor.yml

@@ -63,11 +63,11 @@ install:
   #
   - conda create -q -n test-environment python=%PYTHON_VERSION%
     msinttypes freetype=2.6 "libpng>=1.6.21,<1.7" zlib=1.2 tk=8.5
-    pip setuptools numpy pandas sphinx tornado
+    pip setuptools numpy sphinx tornado
   - activate test-environment
   - echo %PYTHON_VERSION% %TARGET_ARCH%
   # pytest-cov>=2.3.1 due to https://github.com/pytest-dev/pytest-cov/issues/124
-  - pip install -q "pytest>=3.4,!=4.6.0" "pytest-cov>=2.3.1" pytest-rerunfailures pytest-timeout pytest-xdist
+  - pip install -q "pytest>=3.4,!=4.6.0" "pytest-cov>=2.3.1" pytest-rerunfailures pytest-timeout pytest-xdist "pandas!=0.25.0"
 
   # Apply patch to `subprocess` on Python versions > 2 and < 3.6.3
   # https://github.com/matplotlib/matplotlib/issues/9176