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]
@@ -59,7 +61,7 @@ data:
     rpms:
       ruby:
         rationale: An interpreter of object-oriented scripting language
-        ref: changed/i8c-stream-2.6/ruby-2.6.10-109.module+el8.6.0+15475+c55337b4
+        ref: changed/i8-stream-2.6/ruby-2.6.10-109.module+el8.6.0+15475+c55337b4.inferit
         buildorder: 101
         multilib: [x86_64]
       rubygem-abrt:
@@ -76,7 +78,7 @@ data:
         buildorder: 103
       rubygem-mysql2:
         rationale: A simple, fast Mysql library for Ruby, binding to libmysql
-        ref: changed/i8c-stream-2.6/rubygem-mysql2-0.5.2-1.module+el8.1.0+3653+beb38eb0
+        ref: changed/i8-stream-2.6/rubygem-mysql2-0.5.2-1.module+el8.1.0+3653+beb38eb0.inferit
         buildorder: 102
       rubygem-pg:
         rationale: A Ruby interface to the PostgreSQL RDBMS