"Using Renovate to manage updates to go install commands" doesn't quite work when a module import name isn't used

DEBUG: packageFiles with updates (repository=grafana/loki, baseBranch=main)
       "config": {
         "regex": [
           {
             "deps": [
               {
                 "depName": "github.com/go-delve/delve/cmd/dlv",
                 "currentValue": "v1.20.2",
                 "datasource": "go",
                 "replaceString": "go install github.com/go-delve/delve/cmd/dlv@v1.20.2",
                 "updates": [],
                 "packageName": "github.com/go-delve/delve/cmd/dlv",
                 "warnings": [],
                 "versioning": "semver",
                 "sourceUrl": "https://github.com/go-delve/delve"
               }
             ],
             "matchStrings": [
               "go install (?<depName>[^@]+?)@(?<currentValue>v[0-9.-a-zA-Z]+)"
             ],
             "datasourceTemplate": "go",
             "packageFile": "tools/dev/loki-boltdb-storage-s3/dev.dockerfile"
           }
         ]
       }

Should have update to v1.21.0, but isn't detected as /cmd/dlv is there.