setup.py: add pyyaml to install_requires

.travis.yml

@@ -6,7 +6,6 @@ install:
   # Get Migen / LiteX / Cores
   - wget https://raw.githubusercontent.com/enjoy-digital/litex/master/litex_setup.py
   - python3 litex_setup.py init install
-  - python3 -m pip install pyyaml
 
 before_script:
   # Get RISC-V toolchain

setup.py

@@ -19,6 +19,7 @@ setup(
     url="http://enjoy-digital.fr",
     download_url="https://github.com/enjoy-digital/litedram",
     test_suite="test",
+    install_requires=['pyyaml'],
     license="BSD",
     platforms=["Any"],
     keywords="HDL ASIC FPGA hardware design",