Test that GemVersion is hashable

Reference: aboutcode-org/vulnerablecode#926
Reference: aboutcode-org/vulnerablecode#608
Signed-off-by: Philippe Ombredanne <pombredanne@nexb.com>

Author: pombredanne

tests/test_rubygems_gem_version.py

@@ -185,6 +185,9 @@ def test_canonical_segments():
     assert GemVersion("1.0.0.a.1.0").canonical_segments == (1, "a", 1)
     assert GemVersion("1.2.3-1").canonical_segments == (1, 2, 3, "pre", 1)
 
+def test_GemVersion_is_hashable():
+    hash(GemVersion("1.0.0"))
+
 
 def test_frozen_version():
     ver = GemVersion("1.test")