templates: Add Debian and Fedora riscv64 images

The Debian image is the latest from unstable as there's no release yet
for riscv64.

Fedora is a Fedora 42 cloud image hosted at the 'alt' location. It's not
clear how often this will be updated, so the URL may become stale at
some point.

Signed-off-by: Joel Stanley <[email protected]>

Author: shenki

templates/_images/fedora-42.yaml

@@ -7,6 +7,9 @@ images:
   arch: aarch64
   digest: sha256:e10658419a8d50231037dc781c3155aa94180a8c7a74e5cac2a6b09eaa9342b7
 
+- location: https://dl.fedoraproject.org/pub/alt/risc-v/release/42/Cloud/riscv64/images/Fedora-Cloud-Base-Generic-42.20250414-8635a3a5bfcd.riscv64.qcow2
+  arch: riscv64
+  digest: sha256:537c67710f4f1c9112fecaafafc293b649acd1d35b46619b97b5a5a0132241b0
 
 # # NOTE: Intel Mac requires setting vmType to qemu
 # # https://github.com/lima-vm/lima/issues/3334

templates/experimental/debian-sid.yaml

@@ -9,4 +9,7 @@ images:
 - location: https://cloud.debian.org/images/cloud/sid/daily/latest/debian-sid-genericcloud-arm64-daily.qcow2
   arch: aarch64
 
+- location: https://cloud.debian.org/images/cloud/sid/daily/latest/debian-sid-genericcloud-riscv64-daily.qcow2
+  arch: riscv64
+
 mountTypesUnsupported: [9p]