Fix CSV reader adding empty lists in rendering summary (ManimCommunit…

…y#3430)

* Fix CSV reader adding empty files

Fixes issue ManimCommunity#3311

* [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci

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Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>

manim/utils/docbuild/manim_directive.py

@@ -343,6 +343,9 @@ def _log_rendering_times(*args):
 
         print("\nRendering Summary\n-----------------\n")
 
+        # filter out empty lists caused by csv reader
+        data = [row for row in data if row]
+
         max_file_length = max(len(row[0]) for row in data)
         for key, group in it.groupby(data, key=lambda row: row[0]):
             key = key.ljust(max_file_length + 1, ".")