[CI] Add dependency on pyyaml

Pyyaml is needed for primgen (coming next), and for ibex_config.py.
Install it through python-requirements.txt. This requires,
unfortunately, an uninstallation of the distribution-provided version
first (otherwise pip cannot install it).

azure-pipelines.yml

@@ -47,6 +47,8 @@ jobs:
   - bash: |
       curl -L https://download.opensuse.org/repositories/home:phiwag:edatools/xUbuntu_16.04/Release.key | sudo apt-key add -
       sudo sh -c "echo 'deb http://download.opensuse.org/repositories/home:/phiwag:/edatools/xUbuntu_16.04/ /' > /etc/apt/sources.list.d/edatools.list"
+      # Uninstall distribution-provided version to get a newer version through pip
+      sudo apt-get remove -y python3-yaml
       sudo apt-get update
       sudo apt-get install -y \
           python3 \

python-requirements.txt

@@ -7,3 +7,5 @@ git+https://github.com/lowRISC/edalize.git@ot
 
 # Development version with OT-specific changes
 git+https://github.com/lowRISC/fusesoc.git@ot
+
+pyyaml