chore: Remove unnecessary unsafe's

Main.lean

@@ -22,7 +22,7 @@ def parseCommand (s: String): Except String Protocol.Command := do
       return { cmd := s.take offset, payload := payload }
   | .none => throw "Command is empty"
 
-unsafe def loop : MainM Unit := do
+partial def loop : MainM Unit := do
   let state ← get
   let command ← (← IO.getStdin).getLine
   if command.trim.length = 0 then return ()

Test/Main.lean

@@ -6,8 +6,7 @@ import Test.Serial
 
 open Pantograph.Test
 
-unsafe def main := do
-  Lean.enableInitializersExecution
+def main := do
   Lean.initSearchPath (← Lean.findSysroot)
 
   let suites := [