chore: update Go to 1.21.5

No other changes.

Signed-off-by: Andrey Smirnov <andrey.smirnov@siderolabs.com>

Pkgfile

@@ -4,7 +4,7 @@ format: v1alpha2
 
 vars:
   PKGS_PREFIX: ghcr.io/siderolabs
-  PKGS_VERSION: v1.6.0
+  PKGS_VERSION: v1.7.0-alpha.0
 
   # renovate: datasource=git-refs versioning=git depName=https://github.com/awslabs/tc-redirect-tap.git
   tc_redirect_tap_ref: 6827f7b2f5e9ec675cb7dc9bbe4b201c228d565e