Fix unbalanced parens in series-version regex (get_latest_installed_version)

[fsnow]

Problem

get_latest_installed_version() uses a regex to detect a 2-part series version (e.g. 8.3) so it can resolve it to the latest installed patch. The regex has a typo — the first character class is written [0-9)] instead of [0-9]+):

if [[ $version =~ ^([0-9)]\.([0-9]+)(-ent)?$ ]]; then

This does two things:

1. Drops the + quantifier on the major-version digits.
2. Swallows capture group 1's closing paren into the character class.

The result is 3 opening parens but only 2 closing parens, so Bash rejects the whole regex at runtime:

m: line 1506: [[: invalid regular expression `^([0-9)]\.([0-9]+)(-ent)?$': parentheses not balanced

Impact

• m <major>.<minor> series resolution against installed versions is broken.
• The error is printed to stderr on every code path that reaches get_latest_installed_version, including a plain m 8.3.4 install, since the [[ =~ ]] test errors rather than returning false.

Repro

version=8.3
[[ $version =~ ^([0-9)]\.([0-9]+)(-ent)?$ ]]; echo $?
# bash: ... parentheses not balanced
# 2

Fix

Correct the character class to [0-9]+) so group 1 captures the major version, matching how the following lines use BASH_REMATCH[1]/[2]:

-  if [[ $version =~ ^([0-9)]\.([0-9]+)(-ent)?$ ]]; then
+  if [[ $version =~ ^([0-9]+)\.([0-9]+)(-ent)?$ ]]; then

After the fix:

version=8.3
[[ $version =~ ^([0-9]+)\.([0-9]+)(-ent)?$ ]]; echo "$? ${BASH_REMATCH[1]} ${BASH_REMATCH[2]}"
# 0 8 3

One-line change; no behavior change other than making the intended match work and silencing the error.