Use ranges instead of pinned versions in requirements.txt (localstack…

…#2133)

requirements.txt

@@ -16,26 +16,26 @@ awscli>=1.14.18
 boto>=2.49.0
 boto3>=1.9.71                  #basic-lib
 botocore>=1.12.13
-cachetools==3.1.1
+cachetools>=3.1.1,<4.0.0
 coverage==4.5.4
 dnspython==1.16.0              #basic-lib
 docopt>=0.6.2                  #basic-lib
 elasticsearch>=6.0.0,<7.0.0
 flake8>=3.6.0                  #extended-lib
 flake8-quotes>=0.11.0          #extended-lib
-flask==1.0.2
-flask-cors==3.0.3
+flask>=1.0.2
+flask-cors>=3.0.3,<3.1.0
 flask_swagger==0.2.12
 forbiddenfruit==0.1.3
-jsonpatch==1.24
-jsonpath-rw==1.4.0
+jsonpatch>=1.24,<2.0
+jsonpath-rw>=1.4.0,<2.0.0
 localstack-ext[full]>=0.10.51
 localstack-ext>=0.10.51        #basic-lib
 localstack-client>=0.14        #basic-lib
 moto-ext>=1.3.15.5
 nose>=1.3.7
 nose-timer>=0.7.5
-psutil==5.4.8
+psutil>=5.4.8,<6.0.0
 pympler>=0.6
 pyopenssl==17.5.0
 python-coveralls>=2.9.1