fix: Pin protobuf<4.0.0 for Python 2.7 and 3.6 support (#370)

Author: Ferenc-

.circleci/config.yml

@@ -20,10 +20,6 @@ commands:
             virtualenv --python=python2.7 --always-copy venv
             . venv/bin/activate
             pip install 'wheel>=0.29.0'
-            # Install pinned verison of proobuf first,
-            # as opentracing in the core requirements
-            # would pull in a newer one
-            pip install 'protobuf<4.0.0'
             pip install -r requirements.txt
             pip install -r <<parameters.requirements>>
 

instana/version.py

@@ -3,4 +3,4 @@
 
 # Module version file.  Used by setup.py and snapshot reporting.
 
-VERSION = '1.37.2'
+VERSION = '1.37.3'

setup.py

@@ -64,6 +64,7 @@ def check_setuptools():
                         'certifi>=2018.4.16',
                         'fysom>=2.1.2',
                         'opentracing>=2.3.0',
+                        'protobuf<4.0.0',
                         'requests>=2.6.0',
                         'six>=1.12.0',
                         'urllib3<1.27,>=1.26.5'],