fix path for cereal

Author: jeffin143

.ci/linux-steps.yaml

@@ -29,7 +29,7 @@ steps:
 # Configure CMake Args for mlpack.
 - script: |
     unset BOOST_ROOT
-    cd mlpack && mkdir build && cd build && cmake $(CMakeArgs-mlpack) -DCEREAL_INCLUDE_DIR=../cereal-1.3.0/include/ ..
+    cd mlpack && mkdir build && cd build && cmake $(CMakeArgs-mlpack) -DCEREAL_INCLUDE_DIR=../../cereal-1.3.0/include/ ..
   displayName: 'CMake for mlpack'
 
 # Install mlpack

.ci/windows-steps.yaml

@@ -50,7 +50,7 @@ steps:
     cd armadillo-8.400.0/ && cmake $(CMakeGenerator) \
     -DBLAS_LIBRARY:FILEPATH=$(Agent.ToolsDirectory)/OpenBLAS.0.2.14.1/lib/native/lib/x64/libopenblas.dll.a \
     -DLAPACK_LIBRARY:FILEPATH=$(Agent.ToolsDirectory)/OpenBLAS.0.2.14.1/lib/native/lib/x64/libopenblas.dll.a \
-    -DCEREAL_INCLUDE_DIR=$(Agent.ToolsDirectory)\unofficial-flayan-cereal.1.2.2\build\native\include \
+    -DCEREAL_INCLUDE_DIR=$(Agent.ToolsDirectory/unofficial-flayan-cereal.1.2.2/build/native/include \
     -DCMAKE_PREFIX:FILEPATH=../../armadillo \
     -DBUILD_SHARED_LIBS=OFF \
     -DCMAKE_BUILD_TYPE=Release .