Use the bare .Env form for the tap and bucket tokens (#51)

GoReleaser validates that a repository token template is exactly
{{ .Env.VAR_NAME }} and rejects any other interpolation, so the
index .Env form aborted the publish with 'expected {{ .Env.VAR_NAME }}
only'. The token is only rendered when an upload actually happens, and
in CI the secret is always set, so the bare form is safe here.

skip_upload keeps the index .Env form: it is not subject to the token
rule and index degrades to an empty string when the secret is unset, so
an unconfigured fork still skips the upload instead of erroring.

.goreleaser.yaml

@@ -151,7 +151,7 @@ homebrew_casks:
     repository:
       owner: tamnd
       name: homebrew-tap
-      token: '{{ index .Env "HOMEBREW_TAP_GITHUB_TOKEN" }}'
+      token: '{{ .Env.HOMEBREW_TAP_GITHUB_TOKEN }}'
     directory: Casks
     homepage: https://github.com/tamnd/kage
     description: Clone any website for offline viewing, with the JavaScript stripped out
@@ -168,7 +168,7 @@ scoops:
     repository:
       owner: tamnd
       name: scoop-bucket
-      token: '{{ index .Env "SCOOP_BUCKET_GITHUB_TOKEN" }}'
+      token: '{{ .Env.SCOOP_BUCKET_GITHUB_TOKEN }}'
     homepage: https://github.com/tamnd/kage
     description: Clone any website for offline viewing, with the JavaScript stripped out
     license: MIT