Fix Node.js 13 Alpine variant tags

See https://github.com/docker-library/official-images/pull/7429/files#r376126962:

> The Alpine tags for 13 shouldn't be changing since it was updated due to other issues

> that's true... bug in the script (probably due to other v13s being updated)

library/node

@@ -23,12 +23,12 @@ Architectures: amd64, arm32v7, arm64v8, ppc64le, s390x
 GitCommit: 46f5203674c748b0701135c8eeea4b250b3ecb6d
 Directory: 13/buster-slim
 
-Tags: 13.8.0-alpine3.10, 13.8-alpine3.10, 13-alpine3.10, alpine3.10
+Tags: 13.7.0-alpine3.10, 13.7-alpine3.10, 13-alpine3.10, alpine3.10
 Architectures: amd64, arm32v6, arm32v7, arm64v8, i386, ppc64le, s390x
 GitCommit: 975ad7f092d362ade47f4cff6e2897de17be4cc5
 Directory: 13/alpine3.10
 
-Tags: 13.8.0-alpine3.11, 13.8-alpine3.11, 13-alpine3.11, alpine3.11, 13.8.0-alpine, 13.8-alpine, 13-alpine, alpine
+Tags: 13.7.0-alpine3.11, 13.7-alpine3.11, 13-alpine3.11, alpine3.11, 13.7.0-alpine, 13.7-alpine, 13-alpine, alpine
 Architectures: amd64, arm32v6, arm32v7, arm64v8, i386, ppc64le, s390x
 GitCommit: 975ad7f092d362ade47f4cff6e2897de17be4cc5
 Directory: 13/alpine3.11