ci: restrict tag triggers to full semver

- Prevent the floating v1 major tag from cutting a goreleaser release
  or a docker image build

.github/workflows/docker.yml

@@ -5,7 +5,8 @@ on:
     branches:
       - master
     tags:
-      - "v*"
+      # full semver only; the floating major tag (v1) must not trigger builds
+      - "v[0-9]*.[0-9]*.[0-9]*"
   pull_request:
     branches:
       - master

.github/workflows/goreleaser.yml

@@ -3,7 +3,8 @@ name: Goreleaser
 on:
   push:
     tags:
-      - "*"
+      # full semver only; the floating major tag (v1) must not cut a release
+      - "v[0-9]*.[0-9]*.[0-9]*"
 
 permissions:
   contents: write