Fix windows path replacement

[er1c]

This is a partial fix for #488

It bubbles up another error:

WARNING: All illegal access operations will be denied in a future release
[error] java.lang.IllegalArgumentException: requirement failed
[error]         at scala.Predef$.require(Predef.scala:268)
[error]         at com.sksamuel.scrimage.Image$.fromStream(Image.scala:856)
[error]         at com.sksamuel.scrimage.Image$.$anonfun$fromPath$1(Image.scala:878)
[error]         at com.sksamuel.scrimage.Using.using(Using.scala:7)
[error]         at com.sksamuel.scrimage.Using.using$(Using.scala:5)
[error]         at com.sksamuel.scrimage.Image$.using(Image.scala:807)
[error]         at com.sksamuel.scrimage.Image$.fromPath(Image.scala:878)
[error]         at com.sksamuel.scrimage.Image$.fromFile(Image.scala:875)
[error]         at microsites.util.MicrositeHelper.$anonfun$createFavicons$2(MicrositeHelper.scala:232)
[error]         at scala.collection.immutable.List.map(List.scala:286)
[error]         at microsites.util.MicrositeHelper.createFavicons(MicrositeHelper.scala:230)
[error]         at microsites.util.MicrositeHelper.createResources(MicrositeHelper.scala:112)
[error]         at microsites.MicrositeAutoImportSettings.$anonfun$micrositeTasksSettings$1(MicrositeKeys.scala:402)
[error]         at scala.Function1.$anonfun$compose$1(Function1.scala:49)
[error]         at sbt.internal.util.$tilde$greater.$anonfun$$u2219$1(TypeFunctions.scala:62)
[error]         at sbt.std.Transform$$anon$4.work(Transform.scala:67)
[error]         at sbt.Execute.$anonfun$submit$2(Execute.scala:281)
[error]         at sbt.internal.util.ErrorHandling$.wideConvert(ErrorHandling.scala:19)
[error]         at sbt.Execute.work(Execute.scala:290)
[error]         at sbt.Execute.$anonfun$submit$1(Execute.scala:281)
[error]         at sbt.ConcurrentRestrictions$$anon$4.$anonfun$submitValid$1(ConcurrentRestrictions.scala:178)
[error]         at sbt.CompletionService$$anon$2.call(CompletionService.scala:37)
[error]         at java.base/java.util.concurrent.FutureTask.run(FutureTask.java:264)
[error]         at java.base/java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:515)
[error]         at java.base/java.util.concurrent.FutureTask.run(FutureTask.java:264)
[error]         at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1128)
[error]         at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:628)
[error]         at java.base/java.lang.Thread.run(Thread.java:834)
[error] (site / microsite) java.lang.IllegalArgumentException: requirement failed

[sloshy]

Hi @er1c, some changes to the plugin have happened recently that might change what error you are seeing. In particular the exception you're seeing is from the Scrimage library, and we just updated from 2.x to 4.x which behaves somewhat differently. At your convenience could you please see if the error still occurs if you update your local version of this branch? I've just pulled in the latest changes from master. Thanks!