Update go-githubapp to v0.9.1 (#328)

Author: asvoboda

go.mod

@@ -13,7 +13,7 @@ require (
 	github.com/google/go-querystring v1.0.0
 	github.com/gregjones/httpcache v0.0.0-20190611155906-901d90724c79
 	github.com/palantir/go-baseapp v0.2.4
-	github.com/palantir/go-githubapp v0.9.0
+	github.com/palantir/go-githubapp v0.9.1
 	github.com/pkg/errors v0.9.1
 	github.com/rs/zerolog v1.18.0
 	github.com/sergi/go-diff v1.1.0 // indirect

go.sum

@@ -228,8 +228,8 @@ github.com/mwitkow/go-conntrack v0.0.0-20161129095857-cc309e4a2223/go.mod h1:qRW
 github.com/oklog/ulid v1.3.1/go.mod h1:CirwcVhetQ6Lv90oh/F+FBtV6XMibvdAFo93nm5qn4U=
 github.com/palantir/go-baseapp v0.2.4 h1:OtF5jipUF62ZRjLMLODZ2Rq180Kaekqm4pNOUZdOfAU=
 github.com/palantir/go-baseapp v0.2.4/go.mod h1:TSsvmXBDAAu2wZJgWi1/nG+YM5xIOEsXFmLsNoGP5O4=
-github.com/palantir/go-githubapp v0.9.0 h1:5NmPwIUlEh/t0TOm+QoGMwZsjj2HTpgi2SaXLmFl8Do=
-github.com/palantir/go-githubapp v0.9.0/go.mod h1:+reYl6s23olCHWigIXth27wvl0ckoInmZmY+Cyom0Ls=
+github.com/palantir/go-githubapp v0.9.1 h1:XCAKfGshIrwuSmN0nPjj7c6+iHBEtoeRHQ/2/sdKGNA=
+github.com/palantir/go-githubapp v0.9.1/go.mod h1:+reYl6s23olCHWigIXth27wvl0ckoInmZmY+Cyom0Ls=
 github.com/pascaldekloe/goe v0.0.0-20180627143212-57f6aae5913c/go.mod h1:lzWF7FIEvWOWxwDKqyGYQf6ZUaNfKdP144TG7ZOy1lc=
 github.com/pelletier/go-toml v1.2.0/go.mod h1:5z9KED0ma1S8pY6P1sdut58dfprrGBbd/94hg7ilaic=
 github.com/pkg/errors v0.8.0/go.mod h1:bwawxfHBFNV+L2hUp1rHADufV3IMtnDRdf1r5NINEl0=

vendor/github.com/palantir/go-githubapp/appconfig/appconfig.go

@@ -36,7 +36,7 @@ github.com/inconshreveable/mousetrap
 github.com/palantir/go-baseapp/baseapp
 github.com/palantir/go-baseapp/baseapp/datadog
 github.com/palantir/go-baseapp/pkg/errfmt
-# github.com/palantir/go-githubapp v0.9.0
+# github.com/palantir/go-githubapp v0.9.1
 github.com/palantir/go-githubapp/appconfig
 github.com/palantir/go-githubapp/githubapp
 github.com/palantir/go-githubapp/oauth2