main/pstree: update source url

upstream reports "connection refused",
maintainer (fred@thp.uni-due.de) is unreachable

main/pstree/APKBUILD

@@ -9,7 +9,7 @@ arch="all"
 license="GPL"
 depends="!psmisc" # also provides pstree
 subpackages="$pkgname-doc"
-source="ftp://ftp.thp.uni-duisburg.de/pub/source/$pkgname-$pkgver.tar.gz"
+source="https://fossies.org/linux/misc/pstree-$pkgver.tar.gz"
 
 build() {
 	${CC:-gcc} ${CFLAGS} -o "$srcdir"/$pkgname \