golangci: drop outdated govet config

According to https://golangci-lint.run/usage/linters/#govet,
`check-shadowing` no longer exists. Now it should be
```yaml
govet:
  disable: [shadow]
```
but `shadow` is disabled by default. Thus, whole `govet` section is not
needed anymore.

```
$ golangci-lint --version
golangci-lint has version 1.59.1 built with go1.22.3 from 1a55854a on 2024-06-09T18:08:33Z
```

Signed-off-by: Anna Shaleva <[email protected]>

.golangci.yml

@@ -22,9 +22,6 @@ linters-settings:
     # 'default' case is present, even if all enum members aren't listed in the
     # switch
     default-signifies-exhaustive: true
-  govet:
-    # report about shadowed variables
-    check-shadowing: false
 
 linters:
   enable: