fix: serialize patches inside double quotes if there are variables inside (#137)

Old behaviour leads to variable to be serialized always in single quotes
(if shlex decides to quote it). It doesn't allow to expand variables during execution,
so those values should be put inside double quotes instead. This commit
checks if there is sign char in the variable and quotes manually,
otherwise returning shlex call

src/ahriman/models/pkgbuild_patch.py

@@ -43,8 +43,6 @@ class PkgbuildPatch:
     key: str | None
     value: str | list[str]
 
-    quote = shlex.quote
-
     def __post_init__(self) -> None:
         """
         remove empty key
@@ -132,6 +130,24 @@ class PkgbuildPatch:
 
         return cls(key, value())
 
+    @staticmethod
+    def quote(source: str) -> str:
+        """
+        like :func:`shlex.quote()`, but better. The difference in this method from the library one is that it uses
+        double quotes on top level instead of single quotes to allow shell variable substitution
+
+        Args:
+            source(str): source value string to quote
+
+        Returns:
+            str: quoted string
+        """
+        if "$" in source:
+            # copy from library method with double quotes instead
+            return f"""\"{source.replace("\"", "'\"'")}\""""
+        # otherwise just return normal call
+        return shlex.quote(source)
+
     @staticmethod
     def unquote(source: str) -> str:
         """
@@ -175,14 +191,14 @@ class PkgbuildPatch:
             str: serialized key-value pair, print-friendly
         """
         if isinstance(self.value, list):  # list like
-            value = " ".join(map(PkgbuildPatch.quote, self.value))
+            value = " ".join(map(self.quote, self.value))
             return f"""{self.key}=({value})"""
         if self.is_plain_diff:  # no additional logic for plain diffs
             return self.value
         # we suppose that function values are only supported in string-like values
         if self.is_function:
             return f"{self.key} {self.value}"  # no quoting enabled here
-        return f"""{self.key}={PkgbuildPatch.quote(self.value)}"""
+        return f"""{self.key}={self.quote(self.value)}"""
 
     def substitute(self, variables: dict[str, str]) -> str | list[str]:
         """