goreleaser: downcase archive and binary names (#6029)
before:
```
Tendermint_0.34.3_darwin_amd64.tar.gz
-rw-r--r-- 0 runner docker 192329 Jan 19 19:30 CHANGELOG.md
-rw-r--r-- 0 runner docker 321 Jan 19 19:30 CHANGELOG_PENDING.md
-rw-r--r-- 0 runner docker 11382 Jan 19 19:30 LICENSE
-rw-r--r-- 0 runner docker 8165 Jan 19 19:30 README.md
-rwxr-xr-x 0 runner docker 23224320 Jan 19 19:30 tendermint
```
after:
```
tendermint_0.34.3_darwin_amd64.tar.gz
-rw-r--r-- 0 runner docker 192329 Jan 19 19:30 CHANGELOG.md
-rw-r--r-- 0 runner docker 321 Jan 19 19:30 CHANGELOG_PENDING.md
-rw-r--r-- 0 runner docker 11382 Jan 19 19:30 LICENSE
-rw-r--r-- 0 runner docker 8165 Jan 19 19:30 README.md
-rwxr-xr-x 0 runner docker 23224320 Jan 19 19:30 tendermint
```
|