fix(test_capture_pane): use of double env

[zappolowski]

This makes the test fail (at least for me) as it still won't start bash but my login-shell (which is not bash).

[codecov]

Codecov Report

Merging #452 (5783026) into master (3c71322) will increase coverage by 0.02%.
The diff coverage is 100.00%.

❗ Current head 5783026 differs from pull request most recent head b74e428. Consider uploading reports for the commit b74e428 to get more accurate results

@@            Coverage Diff             @@
##           master     #452      +/-   ##
==========================================
+ Coverage   87.44%   87.46%   +0.02%     
==========================================
  Files          20       20              
  Lines        1800     1803       +3     
  Branches      280      280              
==========================================
+ Hits         1574     1577       +3     
  Misses        154      154              
  Partials       72       72              

Impacted Files	Coverage Δ
tests/test_pane.py	100.00% <100.00%> (ø)

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