Add Python 3.7 support (#160)

* Change python version dependency to 3.7

* Add checks for null values of env_vars in batch config

Co-authored-by: ewezy <ziyi.ewe@gojek.com>

sdk/setup.py

@@ -29,5 +29,5 @@
     extras_require={
         'dev': dev_requirements
     },
-    python_requires='>=3.8',
+    python_requires='>=3.7',
 )

sdk/turing/batch/config/config.py

@@ -113,8 +113,13 @@ def job_spec(self) -> turing.generated.models.EnsemblingJobSpec:
         )
 
     def infra_spec(self) -> turing.generated.models.EnsemblerInfraConfig:
+        if self.env_vars is None:
+            env_vars = []
+        else:
+            env_vars = [EnvVar(name=name, value=value) for name, value in self.env_vars.items()]\
+
         return turing.generated.models.EnsemblerInfraConfig(
             service_account_name=self.service_account,
             resources=self.resource_request,
-            env=[EnvVar(name=name, value=value) for name, value in self.env_vars.items()],
+            env=env_vars,
         )