remove extra space before the three-backticks (#172)

there is an extra space before the ending three-backticks of the code block, which causes an abnormal display in the webpage

Author: szcf-weiya

docs/src/tutorials/conversions_views.md

@@ -252,7 +252,7 @@ Stacktrace:
  [1] error(::String) at .\error.jl:33
  [2] pointer_from_objref(::Any) at .\pointer.jl:146
  [3] top-level scope at none:1
- ```
+```
 
 The opposite transformation is `normedview`: