fix: apps/epp_proxy/priv/test_backend_app/Gemfile & apps/epp_proxy/priv/test_backend_app/Gemfile.lock to reduce vulnerabilities

The following vulnerabilities are fixed with an upgrade:
- https://snyk.io/vuln/SNYK-RUBY-RACK-10074187
- https://snyk.io/vuln/SNYK-RUBY-RACK-10303186
- https://snyk.io/vuln/SNYK-RUBY-RACK-13378928
- https://snyk.io/vuln/SNYK-RUBY-RACK-13378930
- https://snyk.io/vuln/SNYK-RUBY-RACK-13378932
- https://snyk.io/vuln/SNYK-RUBY-RACK-13535097
- https://snyk.io/vuln/SNYK-RUBY-RACK-13524628

Author: snyk-bot

apps/epp_proxy/priv/test_backend_app/Gemfile

@@ -6,4 +6,4 @@ gem "puma"
 gem "roda"
 gem "rack-unreloader"
 gem "tilt"
-gem "rackup"
+gem "rackup", ">= 2.3.0"

apps/epp_proxy/priv/test_backend_app/Gemfile.lock

@@ -4,23 +4,24 @@ GEM
     nio4r (2.7.4)
     puma (6.6.0)
       nio4r (~> 2.0)
-    rack (3.1.12)
+    rack (3.2.4)
     rack-unreloader (2.1.0)
-    rackup (2.2.1)
+    rackup (2.3.1)
       rack (>= 3)
     roda (3.90.0)
       rack
     tilt (2.6.0)
 
 PLATFORMS
   aarch64-linux
+  x86_64-linux
 
 DEPENDENCIES
   puma
   rack-unreloader
-  rackup
+  rackup (>= 2.3.0)
   roda
   tilt
 
 BUNDLED WITH
-   2.4.10
+   2.3.27