Fixes multiline strings for Telescope

Fixes #22

lua/yaml_nvim/pair.lua

···
 end
 
 local function clean_up_block_value(value)
+    value = string.gsub(value, "\n", " ")
+
 	if value:sub(1, 1) ~= "|" then
 		return value
 	end

tests/sample.yaml

···
   semifinals:
     - brazil: 1
       germany: 7
+      details:
+        - {
+            stadium: Mineirão
+          }
     - nederland: 0
       argentina: 0
+      details:
+        - {
+             stadium: Itaquerão
+          }