[BUG] HSTS header parsing does not accept spaces between directives

[funkdoodle]

I am running version

./testssl.sh -v | grep from
    testssl.sh       3.2rc3 from https://testssl.sh/dev/

A site that returns a HSTS header with spaces between directives gets reported as a misconfigured HSTS header.
e.g.

Strict-Transport-Security: max-age=31536000 ; includeSubDomains

Expected Behaviour
The header above is valid as per RFC6797, and should have passed the test.

Additional Context
Debug log shows:

|2726>  run_hsts(): hsts_age_sec='31536000 ; includeSubDomains'
|2727>  run_hsts(): hsts_age_sec='31536000 '
|2728>  run_hsts(): [[ 31536000  =~ " ]]
|2733>  run_hsts(): debugme echo 'hsts_age_sec: 31536000 '
|815>   debugme(): [[ 0 -ge 2 ]]
|816>   debugme(): return 0
|2734>  run_hsts(): is_number '31536000 '
|879>   is_number(): [[ 31536000  =~ ^[1-9][0-9]*$ ]]
|881>   is_number(): return 1

The following patch should fix the issue:

diff --git a/testssl.sh b/testssl.sh
index 99cc71b..a0d5578 100755
--- a/testssl.sh
+++ b/testssl.sh
@@ -2724,6 +2724,7 @@ run_hsts() {
           # strict parsing now as suggested in #2381
           hsts_age_sec="${HEADERVALUE#*=}"
           hsts_age_sec=${hsts_age_sec%%;*}
+          hsts_age_sec=$(strip_trailing_space "$hsts_age_sec")
           if [[ $hsts_age_sec =~ \" ]]; then
                # remove first an last " in $hsts_age_sec (borrowed from strip_trailing_space/strip_leading_space):
                hsts_age_sec=$(printf "%s" "${hsts_age_sec#"${hsts_age_sec%%[!\"]*}"}")