community/racket: upgrade to 8.13

riscv64 is having some problems building the Chez Scheme included in this
version of Racket, so we have to disable it for riscv64.

community/racket/APKBUILD

@@ -5,7 +5,7 @@
 # TODO: Install even packages from the full tarball?
 # TODO: Figure out how to run tests.
 pkgname=racket
-pkgver=8.12
+pkgver=8.13
 pkgrel=0
 pkgdesc="general purpose programming language in the Lisp-Scheme family"
 url="https://racket-lang.org/"
@@ -36,7 +36,7 @@ _flags=
 case "$CARCH" in
 	# Racket CS (Chez Scheme backend) is not supported on these platforms,
 	# so build only BC (custom backend).
-	ppc64le | s390x)
+	ppc64le | riscv64 | s390x)
 		pkgdesc="Racket BC - $pkgdesc"
 		license="($license) AND LGPL-3.0-or-later"
 		_flags="--enable-bconly --enable-bcdefault --enable-shared"
@@ -87,5 +87,5 @@ package() {
 }
 
 sha512sums="
-8cddd7fc2743d049f03b393573618e6cc77cb4bedc4066add91458e60dc812a0ecfc91c6eef64242bb6093c7aed4ee2e748f5d961b9254462f55c1202f8de823  racket-minimal-8.12-src.tgz
+f924ffd9277077aeaca72bd440e0d15f75e70cdc70540f584de2d04bcbbc39e1a26c1ecfb7f90b07ff41b9f334a8dd98d23fbe3cb44bcfe53c948d75c08cdbec  racket-minimal-8.13-src.tgz
 "