Collect Alpine vulnerability data from APKBUILD comments

This may be redundant or not but APKBUILD files seem to have secfix info:

https://git.alpinelinux.org/aports/tree/main/asterisk/APKBUILD?id=9d426cf7a7701ee6707224d3e9f6d07553a56de1#n40
```
# secfixes:
# 18.2.1-r0:
# - CVE-2021-26712
# - CVE-2021-26713
# - CVE-2021-26717
# - CVE-2021-26906
# 18.1.1-r0:
# - CVE-2020-35652
# - CVE-2020-35776
# 18.0.1-r0:
# - CVE-2020-28327
# 16.6.2-r0:
# - CVE-2019-18610
# - CVE-2019-18790
# 16.5.1-r0:
# - CVE-2019-15297
# - CVE-2019-15639
# 16.4.1-r0:
# - CVE-2019-12827
# 16.3.0-r0:
# - CVE-2019-7251
# 15.7.1-r0:
# - CVE-2018-19278
```