Set sshkit minimum version to 1.22.2

This includes a fix for a bug in the eviction thread that could cause
this error:

```
[ERROR (IOError): Exception while executing on host foo: closed stream]
```

See https://github.com/capistrano/sshkit/pull/534

Gemfile.lock

@@ -9,7 +9,7 @@ PATH
       dotenv (~> 2.8)
       ed25519 (~> 1.2)
       net-ssh (~> 7.0)
-      sshkit (~> 1.21)
+      sshkit (>= 1.22.2, < 2.0)
       thor (~> 1.2)
       zeitwerk (~> 2.5)
 
@@ -75,6 +75,8 @@ GEM
     mutex_m (0.2.0)
     net-scp (4.0.0)
       net-ssh (>= 2.6.5, < 8.0.0)
+    net-sftp (4.0.0)
+      net-ssh (>= 5.0.0, < 8.0.0)
     net-ssh (7.2.1)
     nokogiri (1.16.0-arm64-darwin)
       racc (~> 1.4)
@@ -151,9 +153,11 @@ GEM
       rubocop-rails
     ruby-progressbar (1.13.0)
     ruby2_keywords (0.0.5)
-    sshkit (1.21.7)
+    sshkit (1.22.2)
+      base64
       mutex_m
       net-scp (>= 1.1.2)
+      net-sftp (>= 2.1.2)
       net-ssh (>= 2.8.0)
     stringio (3.1.0)
     thor (1.3.0)