Fix broken YAML in a way that codecov understands

Theoretically the previous was not a valid YAML at all, but it is
fairly common for parsers to accept it, just in a wrong way. This
results in a configuration where only the last value for duplicate
keys is taken, instead of a hard error.

codecov.yml

@@ -9,18 +9,16 @@ coverage:
     patch:
       default:
         target: 80%
+  ignore:
+    - "projects/SelfTest"
+    - "**/catch_reporter_tap.hpp"
+    - "**/catch_reporter_automake.hpp"
+    - "**/catch_reporter_teamcity.hpp"
+    - "**/external/clara.hpp"
 
 
 codecov:
   branch: master
 
 comment:
   layout: "diff"
-
-coverage:
-  ignore:
-    - "projects/SelfTest"
-    - "**/catch_reporter_tap.hpp"
-    - "**/catch_reporter_automake.hpp"
-    - "**/catch_reporter_teamcity.hpp"
-    - "**/external/clara.hpp"