Adds missing build requirements and updates components refs

- Added mariadb:10.3 build requirement.
  - Added postgresql:10 build requirement.
  - Updated ref for ruby component to fix test issues.
  - Updated ref for rubygem-mysql2 component to fix test issues.

SOURCES/modulemd.src.txt

@@ -13,6 +13,8 @@ data:
     - MIT
   dependencies:
   - buildrequires:
+      mariadb: [10.3]
+      postgresql: [10]
       platform: [el8]
     requires:
       platform: [el8]
@@ -55,7 +57,7 @@ data:
     rpms:
       ruby:
         rationale: An interpreter of object-oriented scripting language
-        ref: changed/i8c-stream-2.7/ruby-2.7.8-139.module+el8.8.0+18745+f1bef313
+        ref: changed/i8-stream-2.7/ruby-2.7.8-139.module+el8.8.0+18745+f1bef313.inferit
         buildorder: 101
         multilib: [x86_64]
       rubygem-abrt:
@@ -72,7 +74,7 @@ data:
         buildorder: 103
       rubygem-mysql2:
         rationale: A simple, fast Mysql library for Ruby, binding to libmysql
-        ref: changed/i8c-stream-2.7/rubygem-mysql2-0.5.3-1.module+el8.3.0+7192+4e3a532a
+        ref: changed/i8-stream-2.7/rubygem-mysql2-0.5.3-1.module+el8.3.0+7192+4e3a532a.inferit
         buildorder: 102
       rubygem-pg:
         rationale: A Ruby interface to the PostgreSQL RDBMS