Bump pyyaml from 3.12 to 5.4 in /Chapter06/requirements

Chapter06/requirements/base.txt

@@ -4,34 +4,80 @@
 #
 #    pip-compile --output-file requirements/base.txt requirements/base.in
 #
-amqp==1.4.9               # via kombu
-anyjson==0.3.3            # via kombu
+amqp==1.4.9
+    # via kombu
+anyjson==0.3.3
+    # via kombu
 bcrypt==3.1.4
-certifi==2017.7.27.1      # via requests
-cffi==1.11.4              # via bcrypt
-chardet==3.0.4            # via requests
-click==6.7                # via flask
-enum-compat==0.0.2        # via eventlet
-eventlet==0.21.0          # via nameko
+    # via -r base.in
+certifi==2017.7.27.1
+    # via requests
+cffi==1.11.4
+    # via bcrypt
+chardet==3.0.4
+    # via requests
+click==6.7
+    # via flask
+enum-compat==0.0.2
+    # via eventlet
+enum34==1.1.10
+    # via enum-compat
+eventlet==0.21.0
+    # via nameko
 flask==0.12.2
-greenlet==0.4.12          # via eventlet
-idna==2.6                 # via requests
-itsdangerous==0.24        # via flask
+    # via -r base.in
+funcsigs==1.0.2
+    # via mock
+greenlet==0.4.12
+    # via eventlet
+idna==2.6
+    # via requests
+itsdangerous==0.24
+    # via flask
 jinja2==2.9.6
-kombu==3.0.37             # via nameko
-markupsafe==1.0           # via jinja2
-mock==2.0.0               # via nameko
+    # via
+    #   -r base.in
+    #   flask
+kombu==3.0.37
+    # via nameko
+markupsafe==1.0
+    # via jinja2
+mock==2.0.0
+    # via nameko
 nameko-sqlalchemy==1.0.0
+    # via -r base.in
 nameko==2.6.0
-path.py==10.4             # via nameko
-pbr==3.1.1                # via mock
+    # via
+    #   -r base.in
+    #   nameko-sqlalchemy
+path.py==10.4
+    # via nameko
+pbr==3.1.1
+    # via mock
 psycopg2==2.7.4
-pycparser==2.18           # via cffi
-pyyaml==3.12              # via nameko
+    # via -r base.in
+pycparser==2.18
+    # via cffi
+pyyaml==5.4
+    # via nameko
 redis==2.10.6
-requests==2.18.4          # via nameko
-six==1.11.0               # via bcrypt, mock, nameko
+    # via -r base.in
+requests==2.18.4
+    # via nameko
+six==1.11.0
+    # via
+    #   bcrypt
+    #   mock
+    #   nameko
 sqlalchemy==1.2.1
-urllib3==1.22             # via requests
-werkzeug==0.12.2          # via flask, nameko
-wrapt==1.10.11            # via nameko
+    # via
+    #   -r base.in
+    #   nameko-sqlalchemy
+urllib3==1.22
+    # via requests
+werkzeug==0.12.2
+    # via
+    #   flask
+    #   nameko
+wrapt==1.10.11
+    # via nameko