FIX: prevents time sniffer to match a date starting with the year

lib/time_sniffer.rb

@@ -312,7 +312,7 @@ class TimeSniffer
   end
 
   DATE_SEPARATOR = /[-\/]/
-  DATE_REGEX = /(\d{1,2})#{DATE_SEPARATOR}(\d{1,2})#{DATE_SEPARATOR}(\d{2,4})/
+  DATE_REGEX = /((?:^|\s)\d{1,2})#{DATE_SEPARATOR}(\d{1,2})#{DATE_SEPARATOR}(\d{2,4})/
 
   matcher(:date, DATE_REGEX) do |m|
     Parser.new(input, @context).parse_range

spec/lib/time_sniffer_spec.rb

@@ -208,4 +208,9 @@ describe TimeSniffer do
   it "should not find a time in random numbers and an emoji" do
     expect_parsed_as_nil("15😊00")
   end
+
+  it "shouldnt match a date starting with the year" do
+    expect_parsed_as_nil("2020-03-27")
+    expect_parsed_as_nil("foo 2020-03-27")
+  end
 end