Update Travis to use Python3.8 and Yara 4 for test

.travis.yml

@@ -6,19 +6,19 @@ cache:
   pip: true
 python:
 - 3.6
-- 3.6-dev
+- 3.8
 before_install:
 - sudo apt-get update -qq
 - sudo apt-get install automake libtool make gcc libmagic-dev -yqq python3-pip unzip upx
-- wget https://github.com/VirusTotal/yara/archive/v3.10.0.tar.gz
-- tar -xzvf v3.10.0.tar.gz
-- cd yara-3.10.0/ && ./bootstrap.sh && ./configure --enable-dotnet --enable-magic
+- wget https://github.com/VirusTotal/yara/archive/v4.0.0.tar.gz
+- tar -xzvf v4.0.0.tar.gz
+- cd yara-4.0.0/ && ./bootstrap.sh && ./configure --enable-dotnet --enable-magic
   && make && sudo make install && cd ../
 - git clone --recursive https://github.com/VirusTotal/yara-python
 - pip3 install pytest codecov pytest-cov
 - cd yara-python
 - python setup.py build --enable-magic --enable-dotnet
-- python setup.py install && cd ../ && rm -rf yara-python && rm -rf yara-3.10.0/
+- python setup.py install && cd ../ && rm -rf yara-python && rm -rf yara-4.0.0/
 - wget https://github.com/kevthehermit/malconf-samples/archive/master.zip && unzip master.zip && mv malconf-samples-master tests/samples/ && rm master.zip
 install:
 - pip install -r requirements.txt