Sort git tags when determining prerelease version

Tags are sorted lexicographically by default, not by version,
so for example right now `git ls-remote` for this repo shows:

```
$ git ls-remote --tags \
  https://github.com/github/copilot-cli \
  | tail -3 | awk -F/ '{print$NF}'
v1.0.8
v1.0.8-0
v1.0.9
```

With the sort option, it shows the correct latest prerelease tags:

```
$ git ls-remote --tags --sort "version:refname" \
  https://github.com/github/copilot-cli \
  | tail -3 | awk -F/ '{print$NF}'
v1.0.12-0
v1.0.12-1
v1.0.12-2
```

This option for git ls-remote was added in git version 2.18.0 in June 2018:
https://github.com/git/git/blob/v2.18.0/Documentation/RelNotes/2.18.0.txt#L69-L70

Author: gulducat

install.sh

@@ -54,7 +54,7 @@ elif [ "${VERSION}" = "prerelease" ]; then
     echo "Error: git is required to install prerelease versions" >&2
     exit 1
   fi
-  VERSION="$(git ls-remote --tags "$GIT_REMOTE" | tail -1 | awk -F/ '{print $NF}')"
+  VERSION="$(git ls-remote --tags --sort "version:refname" "$GIT_REMOTE" | tail -1 | awk -F/ '{print $NF}')"
   if [ -z "$VERSION" ]; then
     echo "Error: Could not determine prerelease version" >&2
     exit 1