Fix binary diff

[ruffsl]

Don't try to encode diff using utf-8 as diff could be from binary file

[codecov]

Codecov Report

Merging #26 (1f7cca2) into master (6d8764a) will increase coverage by 0.01%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master      #26      +/-   ##
==========================================
+ Coverage   97.18%   97.20%   +0.01%     
==========================================
  Files          19       19              
  Lines         569      572       +3     
  Branches       79       82       +3     
==========================================
+ Hits          553      556       +3     
  Misses          9        9              
  Partials        7        7              

Impacted Files	Coverage Δ
colcon_cache/task/lock/git.py	100.00% <100.00%> (ø)

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[ruffsl]

CC @SteveMacenski , This should fix the CI issue with changed binary files in git repos:

�]0;colcon cache [30/32 done] [0 ongoing]�Starting >>> nav2_bringup
--- stderr: nav2_bringup
Traceback (most recent call last):
  File "/usr/lib/python3/dist-packages/colcon_core/executor/__init__.py", line 91, in __call__
    rc = await self.task(*args, **kwargs)
  File "/usr/lib/python3/dist-packages/colcon_core/task/__init__.py", line 93, in __call__
    return await task_method(*args, **kwargs)
  File "/usr/local/lib/python3.8/dist-packages/colcon_cache/task/lock/git.py", line 96, in lock
    self.compute_current_checksums(args, lockfile)
  File "/usr/local/lib/python3.8/dist-packages/colcon_cache/task/lock/git.py", line 127, in compute_current_checksums
    h.update(diff.encode('utf-8'))
UnicodeEncodeError: 'utf-8' codec can't encode characters in position 5484-56349: surrogates not allowed
---
Failed   <<< nav2_bringup [0.02s, exited with code 1]
�]0;colcon cache [30/32 done] [1 ongoing]��]0;colcon cache [31/32 done] [0 ongoing]�Starting >>> nav2_system_tests
--- stderr: nav2_system_tests
Traceback (most recent call last):
  File "/usr/lib/python3/dist-packages/colcon_core/executor/__init__.py", line 91, in __call__
    rc = await self.task(*args, **kwargs)
  File "/usr/lib/python3/dist-packages/colcon_core/task/__init__.py", line 93, in __call__
    return await task_method(*args, **kwargs)
  File "/usr/local/lib/python3.8/dist-packages/colcon_cache/task/lock/git.py", line 96, in lock
    self.compute_current_checksums(args, lockfile)
  File "/usr/local/lib/python3.8/dist-packages/colcon_cache/task/lock/git.py", line 127, in compute_current_checksums
    h.update(diff.encode('utf-8'))
UnicodeEncodeError: 'utf-8' codec can't encode characters in position 788-72001: surrogates not allowed
---
Failed   <<< nav2_system_tests [0.27s, exited with code 1]
�]0;colcon cache [31/32 done] [1 ongoing]��]0;colcon cache [32/32 done] [0 ongoing]�
Summary: 30 packages finished [1.55s]
  2 packages failed: nav2_bringup nav2_system_tests
  2 packages had stderr output: nav2_bringup nav2_system_tests
'utf-8' codec can't encode characters in position 5484-56349: surrogates not allowed

Exited with code exit status 1

https://app.circleci.com/pipelines/github/ros-planning/navigation2/6441/workflows/a98ab0e8-0381-4a3c-a6c6-dacaff5a610d/jobs/23676/parallel-runs/0/steps/0-117

ros-navigation/navigation2#2649 (comment)