kraft.yaml: Use stable version for all components

This has the benefit of not requiring updates whenever there is a new
version release of Unikraft components.

Signed-off-by: Razvan Deaconescu <razvan.deaconescu@cs.pub.ro>
Reviewed-by: Eduard Vintilă <eduard.vintila47@gmail.com>
Approved-by: Alexander Jung <alex@unikraft.org>
Tested-by: Unikraft CI <monkey@unikraft.io>
GitHub-Pull-Request-Closes: #7

kraft.yaml

@@ -1,7 +1,8 @@
+---
 specification: '0.5'
 name: python3
 unikraft:
-  version: '0.4'
+  version: 9bf6e63
   kconfig:
     - CONFIG_LIBUK9P=y
     - CONFIG_LIB9PFS=y
@@ -15,13 +16,18 @@ targets:
   - architecture: x86_64
     platform: kvm
 libraries:
-  pthread-embedded: '0.4'
-  lwip: '0.4'
-  zlib: '0.4'
-  libuuid: '0.4'
-  newlib: '0.4'
+  pthread-embedded:
+    version: stable
+  lwip:
+    version: stable
+  zlib:
+    version: stable
+  libuuid:
+    version: stable
+  newlib:
+    version: stable
   python3:
-    version: '0.4'
+    version: stable
     kconfig:
       - CONFIG_LIBPYTHON3=y
       - CONFIG_LIBPYTHON3_EXTENSIONS=y