Fix installation of gitshow/gitshowview completion symlinks

[hhoffstaette]

Description

Fixes#174
Cleanly applies to both 0.4.x and master.

Type of Change

• Bug fix (targets 0.4.x)

Testing

Added patch to Gentoo packagae, installed & verified that gitshow/gitshowview bash completions now work as expected.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 86.34%. Comparing base (e664ecc) to head (e11ca95).
⚠️ Report is 2 commits behind head on master.

Additional details and impacted files

@@ Coverage Diff @@## master #175 +/- ##
=======================================
Coverage 86.34% 86.34% =======================================
Files 15 15 Lines 8156 8156 Branches 1671 1671 =======================================
Hits 7042 7042 Misses 1114 1114 

Flag	Coverage Δ
unittests	86.34% <ø> (ø)

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[twaugh]

Thanks!