Removes unnecessary rust-toolset:rhel8 dep and updates scopeo ref

SOURCES/modulemd.src.txt

@@ -23,7 +23,6 @@ data:
   - buildrequires:
       go-toolset: [rhel8]
       golang-ecosystem: [1.0]
-      rust-toolset: [rhel8]
       platform: [el8]
     requires:
       platform: [el8]
@@ -110,7 +109,7 @@ data:
         ref: changed/i8c-stream-3.0/runc-1.0.0-73.rc95.module+el8.7.0+16533+44634e24
       skopeo:
         rationale: Primary component of this module
-        ref: changed/i8c-stream-3.0/skopeo-1.2.4-2.module+el8.7.0+16533+44634e24
+        ref: changed/i8-stream-3.0/skopeo-1.2.4-2.module+el8.7.0+16533+44634e24.inferit
       slirp4netns:
         rationale: Primary component of this module
         ref: changed/i8c-stream-3.0/slirp4netns-1.1.8-1.module+el8.7.0+16533+44634e24