Fix NonUniqueSourcesRule for sources with / in the git tag
The rule reports a false positive when the git tag contains a slash and the last part matches the regex, for example:
source=("git+https://salsa.debian.org/debian/distro-info-data.git#tag=debian/$pkgver")
will generate
PKGBUILD (distro-info-data) W: Non-unique source name (0.62). Use a unique filename.
Let's strip everything after hash to avoid this.