Srilankan phone number validation (#7706)

* Add is_srilankan_phone_number.py

* Update is_srilankan_phone_number.py

strings/is_srilankan_phone_number.py

@@ -0,0 +1,35 @@
+import re
+
+
+def is_sri_lankan_phone_number(phone: str) -> bool:
+    """
+    Determine whether the string is a valid sri lankan mobile phone number or not
+    References: https://aye.sh/blog/sri-lankan-phone-number-regex
+
+    >>> is_sri_lankan_phone_number("+94773283048")
+    True
+    >>> is_sri_lankan_phone_number("+9477-3283048")
+    True
+    >>> is_sri_lankan_phone_number("0718382399")
+    True
+    >>> is_sri_lankan_phone_number("0094702343221")
+    True
+    >>> is_sri_lankan_phone_number("075 3201568")
+    True
+    >>> is_sri_lankan_phone_number("07779209245")
+    False
+    >>> is_sri_lankan_phone_number("0957651234")
+    False
+    """
+
+    pattern = re.compile(
+        r"^(?:0|94|\+94|0{2}94)" r"7(0|1|2|4|5|6|7|8)" r"(-| |)" r"\d{7}$"
+    )
+
+    return bool(re.search(pattern, phone))
+
+
+if __name__ == "__main__":
+    phone = "0094702343221"
+
+    print(is_sri_lankan_phone_number(phone))