Implemented better backoff version checking and added unit test

exporter/opentelemetry-exporter-otlp-proto-grpc/pkg_resources/__init__.py

@@ -0,0 +1,23 @@
+
+import toml 
+
+deps  = toml.load('./exporter/opentelemetry-exporter-otlp-proto-grpc/pyproject.toml')['project']
+dependencies = deps['dependencies']
+backoff = dependencies[0].split(';')[0]
+info = backoff.split()
+package_name = info[0]
+package_version = info[-1]
+
+pkgs = dict([(package_name, package_version)])
+
+
+def package_version(r):
+    def wrapper(f):
+        r.version = pkgs[f]        
+        return r
+    return wrapper
+
+@package_version
+def get_distribution(package_name):
+    return pkgs[package_name]
+

exporter/opentelemetry-exporter-otlp-proto-grpc/tests/test_otlp_exporter_mixin.py

@@ -113,3 +113,8 @@ def trailing_metadata(self):
                     "while exporting mock, retrying in 0s."
                 ),
             )
+
+    def test_backoff_version_checking(self):
+        import pkg_resources
+        backoff_version = pkg.get_distribution('backoff').version
+        self.assertEqual(backoff_version, '2.0.0')