Auto merge of #218 - xfix:patch-1, r=jdm

Bump phf_generator generator version to 0.7.22

This is useful for cargo minimal version builds. `phf_generator` in versions before 0.7.22 depended on rand 0.3 which itself depended on libc 0.1.1 that no longer compiles with the newest Rust version.

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Author: bors-servo

string-cache-codegen/Cargo.toml

@@ -14,7 +14,7 @@ path = "lib.rs"
 
 [dependencies]
 string_cache_shared = {path = "../shared", version = "0.3"}
-phf_generator = "0.7.15"
+phf_generator = "0.7.22"
 phf_shared = "0.7.4"
 proc-macro2 = "1"
 quote = "1"