package/libs/pcre2: fix PKG_CPE_ID
cpe:/a:pcre:pcre2 is the correct CPE ID for pcre2:
https://nvd.nist.gov/products/cpe/search/results?keyword=cpe:2.3:a:pcre:pcre2
Fixes: c39b0646f3f2d96d40f601209859175af8537b6d (pcre2: import pcre2 from packages feed)
Signed-off-by: Fabrice Fontaine <[email protected]>