add Accept header to DESCRIBE requests

go.mod

@@ -5,7 +5,7 @@ go 1.12
 require (
 	github.com/alecthomas/template v0.0.0-20190718012654-fb15b899a751 // indirect
 	github.com/alecthomas/units v0.0.0-20190924025748-f65c72e2690d // indirect
-	github.com/aler9/gortsplib v0.0.0-20200831072723-57eae89cc552
+	github.com/aler9/gortsplib v0.0.0-20200831134901-89f0204be80e
 	github.com/aler9/sdp/v3 v3.0.0-20200719093237-2c3d108a7436
 	github.com/davecgh/go-spew v1.1.1 // indirect
 	github.com/stretchr/testify v1.6.1

go.sum

@@ -2,8 +2,8 @@ github.com/alecthomas/template v0.0.0-20190718012654-fb15b899a751 h1:JYp7IbQjafo
 github.com/alecthomas/template v0.0.0-20190718012654-fb15b899a751/go.mod h1:LOuyumcjzFXgccqObfd/Ljyb9UuFJ6TxHnclSeseNhc=
 github.com/alecthomas/units v0.0.0-20190924025748-f65c72e2690d h1:UQZhZ2O0vMHr2cI+DC1Mbh0TJxzA3RcLoMsFw+aXw7E=
 github.com/alecthomas/units v0.0.0-20190924025748-f65c72e2690d/go.mod h1:rBZYJk541a8SKzHPHnH3zbiI+7dagKZ0cgpgrD7Fyho=
-github.com/aler9/gortsplib v0.0.0-20200831072723-57eae89cc552 h1:iSF9Byglyx1yqa32kve+6V49wnfI1PB9ciSUBEUO0b0=
-github.com/aler9/gortsplib v0.0.0-20200831072723-57eae89cc552/go.mod h1:kBMvjIdOHRjLdV+oT28JD72JUPpJuwxOc9u72GG8GpY=
+github.com/aler9/gortsplib v0.0.0-20200831134901-89f0204be80e h1:aCZXDnNPDFltytaHe/yCUmJmd7/fglhwLwStH47U6X8=
+github.com/aler9/gortsplib v0.0.0-20200831134901-89f0204be80e/go.mod h1:kBMvjIdOHRjLdV+oT28JD72JUPpJuwxOc9u72GG8GpY=
 github.com/aler9/sdp/v3 v3.0.0-20200719093237-2c3d108a7436 h1:W0iNErWKvSAyJBNVx+qQoyFrWOFVgS6f/WEME/D3EZc=
 github.com/aler9/sdp/v3 v3.0.0-20200719093237-2c3d108a7436/go.mod h1:OnlEK3QI7YtM+ShZWtGajmOHLZ3bjU80AcIS5e34i1U=
 github.com/davecgh/go-spew v1.1.0 h1:ZDRjVQ15GmhC3fiQ8ni8+OwkZQO4DARzQgrnXU1Liz8=