Add support for gpu-rent.vars and enhance git update functionality

- Updated .gitignore to include gpu-rent.vars.
- Modified env.example to introduce the UPDATE_GIT variable for controlling git updates during execution.
- Implemented Import-GpuRentVars function in gpu-rent.ps1 to load environment variables from gpu-rent.vars.
- Enhanced gpu-rent.sh to support loading variables from gpu-rent.vars and added logic for handling default and extra arguments.
- Updated CLI documentation to reflect the new gpu-rent.vars file and its usage in configuration.
- Improved bootstrap and provisioning logic to conditionally perform git updates based on the new configuration.

src/gpu_rent/tunnel.py

@@ -27,6 +27,27 @@ EXIT_STATUSES = frozenset(
 SHELVED_STATUSES = frozenset({"EXPIRED", "SHELVED", "SHELVED_OFFLOADED"})
 
 
+def _patch_paramiko_for_sshtunnel() -> None:
+    """sshtunnel 0.4 still refs paramiko.DSSKey; Paramiko 4+ removed it."""
+    import paramiko
+
+    if hasattr(paramiko, "DSSKey"):
+        return
+
+    class _DSSKeyRemoved(paramiko.PKey):
+        def __init__(self, *args, **kwargs):
+            raise paramiko.SSHException("DSA keys unsupported (paramiko>=4)")
+
+    paramiko.DSSKey = _DSSKeyRemoved  # type: ignore[attr-defined, assignment]
+
+
+def _ssh_tunnel_forwarder():
+    _patch_paramiko_for_sshtunnel()
+    from sshtunnel import SSHTunnelForwarder
+
+    return SSHTunnelForwarder
+
+
 @dataclass
 class WatchDecision:
     kind: str  # ok | reconnect | unshelve | exit
@@ -51,7 +72,7 @@ def decide_watch(status: str | None, tunnel_alive: bool) -> WatchDecision:
 
 
 def _start_forwarder(cfg: Config, host: str, local_port: int):
-    from sshtunnel import SSHTunnelForwarder
+    SSHTunnelForwarder = _ssh_tunnel_forwarder()
 
     server = SSHTunnelForwarder(
         (host, 22),
@@ -131,7 +152,7 @@ def run_tunnel(
     poll_seconds: float = 30.0,
 ) -> None:
     try:
-        from sshtunnel import SSHTunnelForwarder  # noqa: F401
+        _ssh_tunnel_forwarder()
     except ImportError as exc:
         raise CloudError("Нет sshtunnel. Переустанови пакет: pip install -e .") from exc