[CI] Use gcc-10 to run export_lib tests

.travis.yml

@@ -30,7 +30,7 @@ addons:
   homebrew:
     packages:
       - cmake
-      - gcc@7
+      - gcc@10
       - libomp
       - wget
       - lcov

tests/travis/run_test.sh

@@ -22,7 +22,7 @@ then
   python -m pip install xgboost
   python -m pip install lightgbm codecov
   ./build/treelite_cpp_test
-  export GCC_PATH=gcc-7
+  export GCC_PATH=gcc-10
   PYTHONPATH=./python:./runtime/python python -m pytest --cov=treelite --cov=treelite_runtime -v --fulltrace tests/python
   lcov --directory . --capture --output-file coverage.info
   lcov --remove coverage.info '*dmlccore*' --output-file coverage.info
@@ -92,7 +92,7 @@ then
   conda install -c conda-forge numpy scipy pandas pytest scikit-learn coverage
   python -m pip install xgboost
   python -m pip install lightgbm
-  export GCC_PATH=gcc-7
+  export GCC_PATH=gcc-10
   python -m pytest -v --fulltrace tests/python
 
   # Deploy binary wheel to S3
@@ -124,7 +124,7 @@ if [ ${TASK} == "python_sdist_test" ]; then
   conda install -c conda-forge numpy scipy pandas pytest scikit-learn coverage
   python -m pip install xgboost
   python -m pip install lightgbm
-  export GCC_PATH=gcc-7
+  export GCC_PATH=gcc-10
   python -m pytest -v --fulltrace tests/python
 
   # Deploy source wheel to S3