spec: fix rpm build on Fedora 34

Not proud of the fix but it should work for now. See the comment in the spec
file for more information and also the upstream PR for more context:

getkin/kin-openapi#351

Signed-off-by: Ondřej Budai <ondrej@budai.cz>

osbuild-composer.spec

@@ -110,6 +110,15 @@ sed -i "s$// +build !kolo_xmlrpc_oldapi$// +build kolo_xmlrpc_oldapi$" internal/
 sed -i "s$// +build !azblob_oldapi$// +build azblob_oldapi$" internal/upload/azure/page_blob_url.go
 %endif
 
+%if 0%{?fedora} >= 34
+# Fedora 34 and newer ships a newer version of github.com/getkin/kin-openapi
+# package which has a different API than the older ones. Let's make the auto-
+# generated code compatible by applying some sed magic.
+#
+# Remove when F33 is EOL
+sed -i "s/openapi3.Swagger/openapi3.T/;s/openapi3.NewSwaggerLoader().LoadSwaggerFromData/openapi3.NewLoader().LoadFromData/" internal/cloudapi/openapi.gen.go
+%endif
+
 %build
 %if 0%{?rhel}
 GO_BUILD_PATH=$PWD/_build