UnpackStrategy: Make #dependencies non-nilable

`T.nilable` was removed from the `P7Zip#dependencies` type signature
in a previous commit, as `UnpackStrategy#dependencies` doesn't allow
for a nilable return type. This updates the type signature for the
other `#dependencies` methods to also remove `T.nilable`, as they
would produce a runtime error otherwise.

Library/Homebrew/unpack_strategy/air.rb

@@ -17,7 +17,7 @@ module UnpackStrategy
       path.magic_number.match?(/.{59}#{Regexp.escape(mime_type)}/)
     end
 
-    sig { returns(T.nilable(T::Array[Cask::Cask])) }
+    sig { returns(T::Array[Cask::Cask]) }
     def dependencies
       @dependencies ||= T.let([Cask::CaskLoader.load("adobe-air")], T.nilable(T::Array[Cask::Cask]))
     end

Library/Homebrew/unpack_strategy/cab.rb

@@ -24,7 +24,7 @@ module UnpackStrategy
                       verbose:
     end
 
-    sig { returns(T.nilable(T::Array[Formula])) }
+    sig { returns(T::Array[Formula]) }
     def dependencies
       @dependencies ||= T.let([Formula["cabextract"]], T.nilable(T::Array[Formula]))
     end

Library/Homebrew/unpack_strategy/generic_unar.rb

@@ -16,7 +16,7 @@ module UnpackStrategy
       false
     end
 
-    sig { returns(T.nilable(T::Array[Formula])) }
+    sig { returns(T::Array[Formula]) }
     def dependencies
       @dependencies ||= T.let([Formula["unar"]], T.nilable(T::Array[Formula]))
     end

Library/Homebrew/unpack_strategy/lha.rb

@@ -16,7 +16,7 @@ module UnpackStrategy
       path.magic_number.match?(/\A..-(lh0|lh1|lz4|lz5|lzs|lh\\40|lhd|lh2|lh3|lh4|lh5)-/n)
     end
 
-    sig { returns(T.nilable(T::Array[Formula])) }
+    sig { returns(T::Array[Formula]) }
     def dependencies
       @dependencies ||= T.let([Formula["lha"]], T.nilable(T::Array[Formula]))
     end

Library/Homebrew/unpack_strategy/lzip.rb

@@ -16,7 +16,7 @@ module UnpackStrategy
       path.magic_number.match?(/\ALZIP/n)
     end
 
-    sig { returns(T.nilable(T::Array[Formula])) }
+    sig { returns(T::Array[Formula]) }
     def dependencies
       @dependencies ||= T.let([Formula["lzip"]], T.nilable(T::Array[Formula]))
     end

Library/Homebrew/unpack_strategy/lzma.rb

@@ -16,7 +16,7 @@ module UnpackStrategy
       path.magic_number.match?(/\A\]\000\000\200\000/n)
     end
 
-    sig { returns(T.nilable(T::Array[Formula])) }
+    sig { returns(T::Array[Formula]) }
     def dependencies
       @dependencies ||= T.let([Formula["xz"]], T.nilable(T::Array[Formula]))
     end

Library/Homebrew/unpack_strategy/rar.rb

@@ -16,7 +16,7 @@ module UnpackStrategy
       path.magic_number.match?(/\ARar!/n)
     end
 
-    sig { returns(T.nilable(T::Array[Formula])) }
+    sig { returns(T::Array[Formula]) }
     def dependencies
       @dependencies ||= T.let([Formula["libarchive"]], T.nilable(T::Array[Formula]))
     end

Library/Homebrew/unpack_strategy/xz.rb

@@ -16,7 +16,7 @@ module UnpackStrategy
       path.magic_number.match?(/\A\xFD7zXZ\x00/n)
     end
 
-    sig { returns(T.nilable(T::Array[Formula])) }
+    sig { returns(T::Array[Formula]) }
     def dependencies
       @dependencies ||= T.let([Formula["xz"]], T.nilable(T::Array[Formula]))
     end

Library/Homebrew/unpack_strategy/zstd.rb

@@ -16,7 +16,7 @@ module UnpackStrategy
       path.magic_number.match?(/\x28\xB5\x2F\xFD/n)
     end
 
-    sig { returns(T.nilable(T::Array[Formula])) }
+    sig { returns(T::Array[Formula]) }
     def dependencies
       @dependencies ||= T.let([Formula["zstd"]], T.nilable(T::Array[Formula]))
     end