changed min os to 7

MDFFontDiskLoader.podspec

diff --git a/MDFFontDiskLoader.podspec b/MDFFontDiskLoader.podspec
index c92174a..2d0f113 100644
--- a/MDFFontDiskLoader.podspec
+++ b/MDFFontDiskLoader.podspec
@@ -6,7 +6,7 @@
   s.license      = "Apache 2.0"
   s.homepage     = "https://github.com/material-foundation/material-font-disk-loader-ios"
   s.source       = { :git => "https://github.com/material-foundation/material-font-disk-loader-ios.git", :tag => "v" + s.version.to_s }
-  s.platform     = :ios, "8.0"
+  s.platform     = :ios, "7.0"
   s.requires_arc = true
   s.public_header_files = "src/*.h"
   s.source_files = "src/*.{h,m,mm}", "src/private/*.{h,m,mm}"