Because every version of flutter from sdk depends on meta 1.1.8 and xml >=4.3.0 depends on meta ^1.2.0, flutter from sdk is incompatible with xml >=4.3.0.
And because gpx >=1.0.1+2 depends on xml ^4.3.0, flutter from sdk is incompatible with gpx >=1.0.1+2.
So, because flutter_app depends on both flutter any from sdk and gpx ^1.1.1, version solving failed.
pub get failed (1; So, because flutter_app depends on both flutter any from sdk and gpx ^1.1.1, version solving failed.)
[√] Flutter (Channel stable, 1.20.2, on Microsoft Windows [Version 10.0.18363.1016], locale en-US)
• Flutter version 1.20.2 at C:\src\flutter
• Framework revision bbfbf1770c (6 days ago), 2020-08-13 08:33:09 -0700
• Engine revision 9d5b21729f
• Dart version 2.9.1
[√] Android toolchain - develop for Android devices (Android SDK version 30.0.2)
• Android SDK at C:\Users\LK\AppData\Local\Android\sdk
• Platform android-30, build-tools 30.0.2
• Java binary at: C:\Program Files\Android\Android Studio\jre\bin\java
• Java version OpenJDK Runtime Environment (build 1.8.0_242-release-1644-b01)
• All Android licenses accepted.
[√] Android Studio (version 4.0)
• Android Studio at C:\Program Files\Android\Android Studio
• Flutter plugin version 48.0.2
• Dart plugin version 193.7361
• Java version OpenJDK Runtime Environment (build 1.8.0_242-release-1644-b01)
[!] Connected device
! No devices available
! Doctor found issues in 1 category.