Fix smoke test contains assertions

The existing highlight smoke test contains assertions included newlines.
The newlines are no longer present now we have changed the desired line
length of the output.

To fix this we use the YAML trim annotation `-`, so we're only asserting
the text rather than the text and the trailing newline.

tests/smoke/Commands/dev/highlight.smoke.yaml

@@ -10,7 +10,7 @@ tests:
       - positive/Internal/LiteralInt.juvix
 
     stdout:
-      contains: |
+      contains: |-
         add-text-properties
     exit-status: 0
 
@@ -23,7 +23,7 @@ tests:
       - negative/InfixError.juvix
 
     stdout:
-      contains: |
+      contains: |-
         juvix-goto
     exit-status: 0