Fix typo in nightly branch ref (#1783)

[atalman]

Fix typo in nightly m1 ref
See: pytorch/vision#6158

[parmeet]

LGTM

[codecov]

Codecov Report

Merging #1786 (1469d4c) into release/0.13 (e3819d1) will increase coverage by 0.19%.
The diff coverage is n/a.

@@               Coverage Diff                @@
##           release/0.13    #1786      +/-   ##
================================================
+ Coverage         90.04%   90.23%   +0.19%     
================================================
  Files                55       55              
  Lines              2602     2602              
================================================
+ Hits               2343     2348       +5     
+ Misses              259      254       -5     

Impacted Files	Coverage Δ
torchtext/vocab/vectors.py	89.69% <0.00%> (+3.03%)	⬆️

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