editor: Add python indentation tests (#30902)

This PR add tests for a recent PR: [language: Fix indent suggestions for
significant indented languages like
Python](https://github.com/zed-industries/zed/pull/29625)

It also covers cases from past related issues so that we don't end up
circling back to them on future fixes.

- [Python incorrect auto-indentation for
except:](https://github.com/zed-industries/zed/issues/10832)
- [Python for/while...else indention overridden by if statement
](https://github.com/zed-industries/zed/issues/30795)
- [Python: erroneous indent on newline when comment ends in
:](https://github.com/zed-industries/zed/issues/25416)
- [Newline in Python file does not indent
](https://github.com/zed-industries/zed/issues/16288)
- [Tab Indentation works incorrectly when there are multiple
cursors](https://github.com/zed-industries/zed/issues/26157)

Release Notes:

- N/A

crates/languages/src/python/indents.scm

@@ -1,3 +1,6 @@
+(_ "[" "]" @end) @indent
+(_ "{" "}" @end) @indent
+
 (function_definition
   ":" @start
   body: (block) @indent