nimble uninstall reads .nimble files using nimscript

unrelated test failures were triggered by a missing nim to execute
nimscript to downgrade a removed package

Author: daylinmorgan

src/nimble.nim

@@ -2270,7 +2270,7 @@ when isMainModule:
     # Actions that don't need a Nim binary should not trigger downloading Nim.
     # This avoids e.g. `nimble --version` or `nimble list -i` fetching Nim binaries.
     const actionsNotNeedingNim = {actionRefresh, actionSearch, actionList,
-      actionPath, actionUninstall, actionClean, actionManual,
+      actionPath, actionClean, actionManual,
       actionNil}
     let needsNim = not opt.showVersion and not opt.showHelp and
       opt.action.typ notin actionsNotNeedingNim

src/nimblepkg/nimscriptwrapper.nim

@@ -43,6 +43,7 @@ proc getNimblecache(): string =
 proc execNimscript(nimBin: string,
   nimbleFile, nimsFile, actionName: string, options: Options, isHook: bool
 ): tuple[output: string, exitCode: int, stdout: string] =
+  assert nimBin != ""
   let
     outFile = getNimbleTempDir() & ".out"
     isCustomTask = isCustomTask(actionName, options)