fix: Use different versions of pytest for python 2 and python3 (GoogleCloudPlatform#2558)

* fix: Use different versions of pytest for python 2 and python3

* fix: delete extra pytest dep

* fix: update pytest dependencies in requirements.txt

Author: crwilcox

container_registry/container_analysis/requirements.txt

@@ -1,6 +1,7 @@
 google-cloud-pubsub==1.0.0
 google-cloud-containeranalysis==0.3.0
 grafeas==0.1.0
-pytest==5.1.3
+pytest==5.3.0; python_version > "3.0"
+pytest==4.6.6; python_version < "3.0"
 flaky==3.6.1
 mock==3.0.5

functions/imagemagick/requirements-dev.txt

@@ -1,4 +1,5 @@
 mock==3.0.5
 six==1.12.0
 uuid==1.30
-pytest==5.1.3
+pytest==5.3.0; python_version > "3.0"
+pytest==4.6.6; python_version < "3.0"

run/image-processing/requirements.txt

@@ -1,5 +1,6 @@
 Flask==1.1.1
-pytest==5.1.3
+pytest==5.3.0; python_version > "3.0"
+pytest==4.6.6; python_version < "3.0"
 gunicorn==19.9.0
 google-cloud-vision==0.39.0
 google-cloud-storage==1.19.1

run/logging-manual/requirements.txt

@@ -1,3 +1,4 @@
 Flask==1.1.1
-pytest==5.1.3
+pytest==5.3.0; python_version > "3.0"
+pytest==4.6.6; python_version < "3.0"
 gunicorn==19.9.0

run/pubsub/requirements.txt

@@ -1,3 +1,4 @@
 Flask==1.1.1
-pytest==5.1.3
+pytest==5.3.0; python_version > "3.0"
+pytest==4.6.6; python_version < "3.0"
 gunicorn==19.9.0

testing/requirements.txt

@@ -6,7 +6,8 @@ mock==3.0.5
 mysql-python==1.2.5; python_version < "3.0"
 PyCrypto==2.6.1
 pytest-cov==2.8.1
-pytest==5.2.1
+pytest==5.3.0; python_version > "3.0"
+pytest==4.6.6; python_version < "3.0"
 pyyaml==5.1.2
 responses==0.10.6
 WebTest==2.0.33