Python: Fixed empty multiline strings (#2344)

Author: RunDevelopment

components/prism-python.js

@@ -4,7 +4,7 @@ Prism.languages.python = {
 		lookbehind: true
 	},
 	'string-interpolation': {
-		pattern: /(?:f|rf|fr)(?:("""|''')[\s\S]+?\1|("|')(?:\\.|(?!\2)[^\\\r\n])*\2)/i,
+		pattern: /(?:f|rf|fr)(?:("""|''')[\s\S]*?\1|("|')(?:\\.|(?!\2)[^\\\r\n])*\2)/i,
 		greedy: true,
 		inside: {
 			'interpolation': {
@@ -27,7 +27,7 @@ Prism.languages.python = {
 		}
 	},
 	'triple-quoted-string': {
-		pattern: /(?:[rub]|rb|br)?("""|''')[\s\S]+?\1/i,
+		pattern: /(?:[rub]|rb|br)?("""|''')[\s\S]*?\1/i,
 		greedy: true,
 		alias: 'string'
 	},

components/prism-python.min.js

@@ -144,4 +144,4 @@ f'{(lambda x: x*2)(3)}'
 
 ----------------------------------------------------
 
-Checks for string interpolation.
+Checks for string interpolation.

tests/languages/python/string-interpolation_feature.test

@@ -1,7 +1,9 @@
+""""""
 """foobar"""
 """fo"o
 #bar
 baz"""
+''''''
 '''foobar'''
 '''fo'o
 #bar
@@ -10,12 +12,14 @@ baz'''
 ----------------------------------------------------
 
 [
+	["triple-quoted-string", "\"\"\"\"\"\""],
 	["triple-quoted-string", "\"\"\"foobar\"\"\""],
 	["triple-quoted-string", "\"\"\"fo\"o\r\n#bar\r\nbaz\"\"\""],
+	["triple-quoted-string", "''''''"],
 	["triple-quoted-string", "'''foobar'''"],
 	["triple-quoted-string", "'''fo'o\r\n#bar\r\nbaz'''"]
 ]
 
 ----------------------------------------------------
 
-Checks for triple-quoted strings.
+Checks for triple-quoted strings.