Add scalafmt (#179)

Nothing changes besides codes been formatted.

I copied `.scalafmt` from mill and did very little tunings for
consistency and readability.

My local test results

```sh
$ ./mill -i __.publishArtifacts + __.test

[418/420] requests[2.13.15].test.test
[418] 
[420/420] requests[3.3.4].test.test
[420] 
[417/420] requests[2.12.20].test.test
[417] 
[420/420] ==================================================================== __.publishArtifacts + __.test ======================================================================= 1s
```

My local binary compatibility check results

```
$ ./mill -i __.mimaReportBinaryIssues
[build.mill-64/68] compile
[build.mill-64] [info] compiling 1 Scala source to /home/lqhuang/Git/requests-scala/out/mill-build/compile.dest/classes ...
[build.mill-64] [info] done compiling
[211/212] requests.jvm[2.12.20].mimaReportBinaryIssues
[210/212] requests.jvm[2.13.15].mimaReportBinaryIssues
[212/212] requests.jvm[3.3.4].mimaReportBinaryIssues
[211] Scanning binary compatibility in /home/lqhuang/Git/requests-scala/out/requests/jvm/2.12.20/compile.dest/classes ...
[210] Scanning binary compatibility in /home/lqhuang/Git/requests-scala/out/requests/jvm/2.13.15/compile.dest/classes ...
[212] Scanning binary compatibility in /home/lqhuang/Git/requests-scala/out/requests/jvm/3.3.4/compile.dest/classes ...
[210] Binary compatibility check passed
[211] Binary compatibility check passed
[212] Binary compatibility check passed
[212/212] ============================== __.mimaReportBinaryIssues ============================== 8s
```

.gitignore

@@ -1,11 +1,13 @@
 target/
 *.iml
-.idea
+.idea/
+.vscode/
 .settings
 .classpath
 .project
 .cache
 .sbtserver
+.scala-build/
 project/.sbtserver
 tags
 nohup.out

.scalafmt.conf

@@ -0,0 +1,12 @@
+version = "3.8.3"
+
+maxColumn = 100
+runner.dialect = scala213
+
+newlines.beforeCurlyLambdaParams = multilineWithCaseOnly
+rewrite.trailingCommas.style = always
+
+assumeStandardLibraryStripMargin = true
+docstrings.style = Asterisk
+
+project.git = true

build.mill

@@ -1,7 +1,8 @@
 package build
 
 import mill._
-import mill.scalalib._
+import scalalib._
+import scalanativelib._
 import mill.scalalib.publish.{Developer, License, PomSettings, VersionControl}
 
 import $ivy.`de.tototec::de.tobiasroeser.mill.vcs.version::0.4.1`

requests/src/requests/Exceptions.scala

@@ -1,18 +1,29 @@
 package requests
 
 // base class for all custom exceptions thrown by requests.
-class RequestsException(val message: String, val cause: Option[Throwable] = None) extends Exception(message, cause.getOrElse(null))
+class RequestsException(
+    val message: String,
+    val cause: Option[Throwable] = None,
+) extends Exception(message, cause.getOrElse(null))
 
-class TimeoutException(val url: String, val readTimeout: Int, val connectTimeout: Int)
-extends RequestsException(s"Request to $url timed out. (readTimeout: $readTimeout, connectTimout: $connectTimeout)")
+class TimeoutException(
+    val url: String,
+    val readTimeout: Int,
+    val connectTimeout: Int,
+) extends RequestsException(
+      s"Request to $url timed out. (readTimeout: $readTimeout, connectTimout: $connectTimeout)",
+    )
 
 class UnknownHostException(val url: String, val host: String)
-extends RequestsException(s"Unknown host $host in url $url")
+    extends RequestsException(s"Unknown host $host in url $url")
 
 class InvalidCertException(val url: String, cause: Throwable)
-extends RequestsException(s"Unable to validate SSL certificates for $url", Some(cause))
+    extends RequestsException(
+      s"Unable to validate SSL certificates for $url",
+      Some(cause),
+    )
 
 class RequestFailedException(val response: Response)
-extends RequestsException(
-  s"Request to ${response.url} failed with status code ${response.statusCode}\n${response.text()}"
-)
+    extends RequestsException(
+      s"Request to ${response.url} failed with status code ${response.statusCode}\n${response.text()}",
+    )