Add Python literal string interpolation pattern

CHANGELOG.rst

@@ -43,6 +43,7 @@ Added
 - Missing patterns for Python:
    - `dict_pattern`
    - `import_from_statement`
+   - `interpolation` (literal string interpolation)
    - `list_pattern`
    - `tuple_pattern`
 - Missing patterns for Rust:

queries/python/rainbow-delimiters.scm

@@ -68,3 +68,8 @@
 (import_from_statement
   "(" @delimiter
   ")" @delimiter @sentinel) @container
+
+(string
+  (interpolation
+    "{" @delimiter
+    "}" @delimiter @sentinel) @container)

test/highlight/python/regular.py

@@ -44,3 +44,6 @@ print(zero[zero[zero[0]]])
 
 print(2 + ((((3)))))
 print(len(my_list))
+
+# Format-string with embedded delimiters
+print(f'The sum of 2 and 3 is {2 + (1 + 2)}')