etl: bump version from 1.0.0 to 2.0.1 ( (#866)

It seems that only a version bump is necessary.

Latest changes to this problem:

- 1.0.0 to 1.0.1, descriptions too long: exercism/problem-specifications#1526
- 1.0.1 to 2.0.0, change input JSON format: exercism/problem-specifications#1536
- 2.0.0 to 2.0.1, capitalize Scrabble: exercism/problem-specifications#1575

Author: thalesmg

exercises/etl/package.yaml

@@ -1,5 +1,5 @@
 name: etl
-version: 1.0.0.5
+version: 2.0.1.6
 
 dependencies:
   - base

exercises/etl/test/Tests.hs

@@ -15,7 +15,7 @@ specs =
 
   describe "transform" $ do
 
-    it "a single letter" $
+    it "single letter" $
       transform (fromList [(1, "A")])
       `shouldBe` fromList [('a', 1)]