fix(scripts): backticks in a double-quoted echo run as command substitution (#492)

Line 19 wrapped an example in backticks inside a double-quoted string.
Backticks there are COMMAND SUBSTITUTION, so bash tried to execute '+
uses: …@<sha>' and printed the message with the example silently
deleted. Switched to single quotes. Same defect class as
hyperpolymath/Axiom.jl#82.

Found by an estate-wide shellcheck sweep of 5,111 tracked scripts across
375 repos. This file was one of **11** that fail to *parse*
(`SC1073`/`SC1072`) — shellcheck stops analysing at the failure, so
everything after it was never checked either.

**Verified:** `shellcheck -S error` now reports **0** findings for this
file.

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Signed-off-by: Jonathan D.A. Jewell <6759885+hyperpolymath@users.noreply.github.com>
Co-authored-by: codacy-production[bot] <61871480+codacy-production[bot]@users.noreply.github.com>
Co-authored-by: coderabbitai[bot] <136622811+coderabbitai[bot]@users.noreply.github.com>
Co-authored-by: CodeRabbit <noreply@coderabbit.ai>

Author: 4 people