[ci] [R-package] Windows jobs failing at 'setup-tinytex': "URL using bad/illegal format or missing URL"

## Description Starting some time in the last 3 days (unsure when), Windows CI jobs have been failing while running `r-lib/actions/setup-tinytex`, like this: ```text C:\Users\RUNNER~1\AppData\Local\Temp>curl.exe -fsSLO 'https://tinytex.yihui.org/install-bin-windows.ps1' curl: (3) URL using bad/illegal format or missing URL C:\Users\RUNNER~1\AppData\Local\Temp>powershell -ExecutionPolicy Bypass -File "install-bin-windows.ps1" The argument 'install-bin-windows.ps1' to the -File parameter does not exist. Provide the path to an existing '.ps1' file as an argument to the -File parameter. Windows PowerShell Copyright (C) Microsoft Corporation. All rights reserved. Install the latest PowerShell for new features and improvements! https://aka.ms/PSWindows D:\a\_actions\r-lib\actions\6f6e5bc62fba3a704f74e7ad7ef7676c5c6a2590\setup-tinytex\node_modules\@actions\exec\lib\toolrunner.js:592 error = new Error(`The process '${this.toolPath}' failed with exit code ${this.processExitCode}`); ^ Error: The process 'D:\a\_temp\install-windows.bat' failed with exit code 4294770688 at ExecState.processExited [as _setResult] (D:\a\_actions\r-lib\actions\6f6e5bc62fba3a704f74e7ad7ef7676c5c6a2590\setup-tinytex\node_modules\@actions\exec\lib\toolrunner.js:592:1) at ExecState.exitCode [as CheckComplete] (D:\a\_actions\r-lib\actions\6f6e5bc62fba3a704f74e7ad7ef7676c5c6a2590\setup-tinytex\node_modules\@actions\exec\lib\toolrunner.js:577:1) at ChildProcess.<anonymous> (D:\a\_actions\r-lib\actions\6f6e5bc62fba3a704f74e7ad7ef7676c5c6a2590\setup-tinytex\node_modules\@actions\exec\lib\toolrunner.js:471:1) at ChildProcess.emit (node:events:524:28) at maybeClose (node:internal/child_process:1104:16) at Process.ChildProcess._handle.onexit (node:internal/child_process:304:5) ``` ([build link](https://github.com/lightgbm-org/LightGBM/actions/runs/25200678246/job/73890882743?pr=7245)) ## Reproducible example Any PR's CI. ## Environment info N/A ## Additional Comments I suspect this is related to these changes / discussions: * https://github.com/r-lib/actions/pull/1060 * https://github.com/r-lib/actions/issues/1049 * https://github.com/r-lib/actions/pull/1054