Clean up build tags

- Remove old-style build tags (the +build syntax has become obsolete with 1.17)
- Remove redundant build tags from '*_windows.go' files

pkg/commands/oscommands/cmd_obj_runner_windows.go

@@ -0,0 +1,10 @@
+package oscommands
+
+import (
+	"os/exec"
+)
+
+func (self *cmdObjRunner) getCmdHandlerPty(cmd *exec.Cmd) (*cmdHandler, error) {
+	// We don't have PTY support on Windows yet, so we just return a non-PTY handler.
+	return self.getCmdHandlerNonPty(cmd)
+}